diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/ActivityInfoProviderService.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/ActivityInfoProviderService.java
index d1e156a447..1a59a0fc93 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/ActivityInfoProviderService.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/ActivityInfoProviderService.java
@@ -76,9 +76,13 @@ public interface ActivityInfoProviderService {
                     code = 400,
                     message = "Bad Request. \n Invalid request or validation error.",
                     response = ErrorResponse.class),
+            @ApiResponse(
+                    code = 401,
+                    message = ". \n Invalid request or validation error."),
             @ApiResponse(
                     code = 404,
-                    message = "Not Found. \n No activity is found under the provided id."),
+                    message = "Not Found. \n No activity is found under the provided id.",
+                    response = ErrorResponse.class),
             @ApiResponse(
                     code = 406,
                     message = "Not Acceptable.\n The requested media type is not supported"),
@@ -131,6 +135,10 @@ public interface ActivityInfoProviderService {
                     code = 304,
                     message = "Not Modified. \n Empty body because the client has already the latest version of " +
                             "the requested resource."),
+            @ApiResponse(
+                    code = 404,
+                    message = "Not Found. \n No activities found.",
+                    response = ErrorResponse.class),
             @ApiResponse(
                     code = 406,
                     message = "Not Acceptable.\n The requested media type is not supported"),
@@ -147,11 +155,6 @@ public interface ActivityInfoProviderService {
                             "should be provided in unix format in seconds.",
                     required = false)
             @QueryParam("timestamp") long timestamp,
-            @ApiParam(
-                    name = "If-Modified-Since",
-                    value = "Validates if the requested variant has not been modified since the time specified",
-                    required = false)
-            @HeaderParam("If-Modified-Since") String ifModifiedSince,
             @ApiParam(
                     name = "offset",
                     value = "Starting point within the complete list of items qualified.",
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/DeviceManagementService.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/DeviceManagementService.java
index 41937a455f..ebd34eb8c9 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/DeviceManagementService.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/DeviceManagementService.java
@@ -76,13 +76,24 @@ public interface DeviceManagementService {
                     }),
             @ApiResponse(
                     code = 304,
-                    message = "Not Modified. \n Empty body because the client has already the latest version of the requested resource."),
+                    message = "Not Modified. \n Empty body because the client has already the latest version of " +
+                            "the requested resource."),
+            @ApiResponse(
+                    code = 400,
+                    message = "The incoming request has more than one selection criteria defined through query" +
+                            " parameters.",
+                    response = ErrorResponse.class),
+            @ApiResponse(
+                    code = 404,
+                    message = "No device is currently enrolled with the server.",
+                    response = ErrorResponse.class),
             @ApiResponse(
                     code = 406,
                     message = "Not Acceptable.\n The requested media type is not supported"),
             @ApiResponse(
                     code = 500,
-                    message = "Internal Server ErrorResponse. \n Server error occurred while fetching the device list.")
+                    message = "Internal Server ErrorResponse. \n Server error occurred while fetching the device list.",
+                    response = ErrorResponse.class)
     })
     @Permission(scope = "device-list", permissions = {"/permission/admin/device-mgt/admin/devices/list"})
     Response getDevices(
@@ -127,141 +138,6 @@ public interface DeviceManagementService {
                     required = false)
             @QueryParam("limit") int limit);
 
-//    @GET
-//    @Path("{type}/{id}/info")
-//    @ApiOperation(
-//            consumes = MediaType.APPLICATION_JSON,
-//            produces = MediaType.APPLICATION_JSON,
-//            httpMethod = "GET",
-//            value = "Retrieve devices information from the supplied device identifier.",
-//            notes = "This will return device information such as CPU usage, memory usage etc for supplied device " +
-//                    "identifier.",
-//            tags = "Device Management")
-//    @ApiResponses(
-//            value = {
-//                    @ApiResponse(
-//                            code = 200,
-//                            message = "OK. \n Information of the submitted list of devices is returned",
-//                            response = DeviceInfo.class,
-//                            responseHeaders = {
-//                                    @ResponseHeader(
-//                                            name = "Content-Type",
-//                                            description = "The content type of the body"),
-//                                    @ResponseHeader(
-//                                            name = "ETag",
-//                                            description = "Entity Tag of the response resource.\n" +
-//                                                    "Used by caches, or in conditional requests."),
-//                                    @ResponseHeader(
-//                                            name = "Last-Modified",
-//                                            description = "Date and time the resource has been modified the last time.\n" +
-//                                                    "Used by caches, or in conditional requests.")}),
-//                    @ApiResponse(
-//                            code = 303,
-//                            message = "See Other. \n Source can be retrieved from the URL specified at the Location header.",
-//                            responseHeaders = {
-//                                    @ResponseHeader(
-//                                            name = "Content-Location",
-//                                            description = "The Source URL of the document.")}),
-//                    @ApiResponse(
-//                            code = 304,
-//                            message = "Not Modified. \n " +
-//                                    "Empty body because the client already has the latest version of the requested resource."),
-//                    @ApiResponse(
-//                            code = 400,
-//                            message = "Bad Request. \n Invalid request or validation error."),
-//                    @ApiResponse(
-//                            code = 404,
-//                            message = "Not Found. \n No device is found under the provided type and id."),
-//                    @ApiResponse(
-//                            code = 406,
-//                            message = "Not Acceptable. \n The requested media type is not supported."),
-//                    @ApiResponse(
-//                            code = 500,
-//                            message = "Internal Server ErrorResponse. \n " +
-//                                    "Server error occurred while retrieving information of the list of the devices submitted.",
-//                            response = ErrorResponse.class)
-//            })
-//    @Permission(scope = "device-info", permissions = {"/permission/admin/device-mgt/admin/devices/list"})
-//    Response getDeviceInfo(
-//            @ApiParam(
-//                    name = "type",
-//                    value = "The device type, such as ios, android or windows.",
-//                    required = true)
-//            @PathParam("type") String type,
-//            @ApiParam(
-//                    name = "id",
-//                    value = "The device identifier of the device.",
-//                    required = true)
-//            @PathParam("id") String id,
-//            @ApiParam(
-//                    name = "If-Modified-Since",
-//                    value = "Validates if the requested variant has not been modified since the time specified",
-//                    required = false)
-//            @HeaderParam("If-Modified-Since") String ifModifiedSince);
-
-//    @POST
-//    @Path("/get-info")
-//    @ApiOperation(
-//            consumes = MediaType.APPLICATION_JSON,
-//            produces = MediaType.APPLICATION_JSON,
-//            httpMethod = "POST",
-//            value = "Retrieve devices information from the supplied device identifies.",
-//            notes = "This will return device information such as CPU usage, memory usage etc for supplied device " +
-//                    "identifiers.",
-//            tags = "Device Management")
-//    @ApiResponses(
-//            value = {
-//                    @ApiResponse(
-//                            code = 200,
-//                            message = "OK. \n Information of the submitted list of devices is returned",
-//                            response = DeviceInfo.class,
-//                            responseContainer = "List",
-//                            responseHeaders = {
-//                                    @ResponseHeader(
-//                                            name = "Content-Type",
-//                                            description = "The content type of the body"),
-//                                    @ResponseHeader(
-//                                            name = "ETag",
-//                                            description = "Entity Tag of the response resource.\n" +
-//                                                    "Used by caches, or in conditional requests."),
-//                                    @ResponseHeader(
-//                                            name = "Last-Modified",
-//                                            description = "Date and time the resource has been modified the last time.\n" +
-//                                                    "Used by caches, or in conditional requests.")}),
-//                    @ApiResponse(
-//                            code = 303,
-//                            message = "See Other. \n Source can be retrieved from the URL specified at the Location header.",
-//                            responseHeaders = {
-//                                    @ResponseHeader(
-//                                            name = "Content-Location",
-//                                            description = "The Source URL of the document.")}),
-//                    @ApiResponse(
-//                            code = 304,
-//                            message = "Not Modified. \n " +
-//                                    "Empty body because the client already has the latest version of the requested resource."),
-//                    @ApiResponse(
-//                            code = 400,
-//                            message = "Bad Request. \n Invalid request or validation error."),
-//                    @ApiResponse(
-//                            code = 406,
-//                            message = "Not Acceptable. \n The requested media type is not supported."),
-//                    @ApiResponse(
-//                            code = 500,
-//                            message = "Internal Server ErrorResponse. \n " +
-//                                    "Server error occurred while retrieving information of the list of the devices submitted.")
-//            })
-//    @Permission(scope = "device-info", permissions = {"/permission/admin/device-mgt/admin/devices/list"})
-//    Response getDevicesInfo(
-//            @ApiParam(
-//                    name = "If-Modified-Since",
-//                    value = "Timestamp of the last modified date",
-//                    required = false)
-//            @HeaderParam("If-Modified-Since") String timestamp,
-//            @ApiParam(
-//                    name = "deviceIds",
-//                    value = "List of device identifiers",
-//                    required = true) List<DeviceIdentifier> deviceIds);
-
 
     @GET
     @Path("/{type}/{id}")
@@ -292,11 +168,16 @@ public interface DeviceManagementService {
                             }),
                     @ApiResponse(
                             code = 304,
-                            message = "Not Modified. \n " +
-                                    "Empty body because the client already has the latest version of the requested resource."),
+                            message = "Not Modified. Empty body because the client already has the latest " +
+                                    "version of the requested resource."),
+                    @ApiResponse(
+                            code = 400,
+                            message = "Bad Request. \n Invalid request or validation error.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 404,
-                            message = "Not Found. \n No device is found under the provided type and id."),
+                            message = "Not Found. \n No device is found under the provided type and id.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 500,
                             message = "Internal Server ErrorResponse. \n " +
@@ -323,94 +204,6 @@ public interface DeviceManagementService {
                     required = false)
             @HeaderParam("If-Modified-Since") String ifModifiedSince);
 
-//    @GET
-//    @Path("/{type}/{id}/location")
-//    @ApiOperation(
-//            consumes = MediaType.APPLICATION_JSON,
-//            produces = MediaType.APPLICATION_JSON,
-//            httpMethod = "GET",
-//            value = "Get the device location of a given device and a device type.",
-//            notes = "This will return the device location including latitude and longitude as well the "
-//                    + "physical address.",
-//            tags = "Device Management")
-//    @ApiResponses(
-//            value = {
-//                    @ApiResponse(
-//                            code = 200,
-//                            message = "Successfully fetched the device location.",
-//                            response = DeviceLocation.class),
-//                    @ApiResponse(
-//                            code = 304,
-//                            message = "Not Modified. \n " +
-//                                    "Empty body because the client already has the latest version of the requested resource."),
-//                    @ApiResponse(
-//                            code = 404,
-//                            message = "Not Found. \n No device is found under the provided type and id."),
-//                    @ApiResponse(
-//                            code = 500,
-//                            message = "ErrorResponse occurred while getting the device location.",
-//                            response = ErrorResponse.class)
-//            })
-//    @Permission(scope = "device-info", permissions = {"/permission/admin/device-mgt/admin/devices/list"})
-//    Response getDeviceLocation(
-//            @ApiParam(
-//                    name = "type",
-//                    value = "The device type, such as ios, android or windows.",
-//                    required = true)
-//            @PathParam("type") String type,
-//            @ApiParam(
-//                    name = "id",
-//                    value = "The device identifier of the device.",
-//                    required = true)
-//            @PathParam("id") String id,
-//            @ApiParam(
-//                    name = "If-Modified-Since",
-//                    value = "Validates if the requested variant has not been modified since the time specified",
-//                    required = false)
-//            @HeaderParam("If-Modified-Since") String ifModifiedSince);
-
-
-//    @POST
-//    @Path("/locations")
-//    @ApiOperation(
-//            consumes = MediaType.APPLICATION_JSON,
-//            produces = MediaType.APPLICATION_JSON,
-//            httpMethod = "POST",
-//            value = "Get the device location of a given devices and a device type.",
-//            notes = "This will return the device locations including latitude and longitude as well the "
-//                    + "physical address of the given devices.",
-//            tags = "Device Management")
-//    @ApiResponses(
-//            value = {
-//                    @ApiResponse(
-//                            code = 200,
-//                            message = "Successfully fetched the device location.",
-//                            response = DeviceLocation.class,
-//                            responseContainer = "List"),
-//                    @ApiResponse(
-//                            code = 304,
-//                            message = "Not Modified. \n " +
-//                                    "Empty body because the client already has the latest version of the requested resource."),
-//                    @ApiResponse(
-//                            code = 404,
-//                            message = "Location details are not available for the given devices."),
-//                    @ApiResponse(
-//                            code = 500,
-//                            message = "ErrorResponse occurred while getting the device location.",
-//                            response = ErrorResponse.class)
-//            })
-//    @Permission(scope = "device-info", permissions = {"/permission/admin/device-mgt/admin/devices/list"})
-//    Response getDeviceLocations(
-//            @ApiParam(
-//                    name = "deviceIds",
-//                    value = "List of device identifiers",
-//                    required = true) List<DeviceIdentifier> deviceIds,
-//            @ApiParam(
-//                    name = "If-Modified-Since",
-//                    value = "Validates if the requested variant has not been modified since the time specified",
-//                    required = false)
-//            @HeaderParam("If-Modified-Since") String ifModifiedSince);
-
     @GET
     @Path("/{type}/{id}/features")
     @ApiOperation(
@@ -459,7 +252,8 @@ public interface DeviceManagementService {
                             response = ErrorResponse.class),
                     @ApiResponse(
                             code = 404,
-                            message = "Not Found. \n Device of which the feature list is requested, is not found."),
+                            message = "Not Found. \n Device of which the feature list is requested, is not found.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 406,
                             message = "Not Acceptable. \n The requested media type is not supported."),
@@ -525,6 +319,11 @@ public interface DeviceManagementService {
                             code = 400,
                             message = "Bad Request. \n Invalid request or validation error.",
                             response = ErrorResponse.class),
+                    @ApiResponse(
+                            code = 404,
+                            message = "Not Acceptable.\n TIt is likely that no device is found upon the " +
+                                    "provided filters",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 406,
                             message = "Not Acceptable.\n The requested media type is not supported"),
@@ -600,7 +399,8 @@ public interface DeviceManagementService {
                             response = ErrorResponse.class),
                     @ApiResponse(
                             code = 404,
-                            message = "Not Found. \n Device of which the application list is requested, is not found."),
+                            message = "Not Found. \n Device of which the application list is requested, is not found.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 406,
                             message = "Not Acceptable. \n The requested media type is not supported."),
@@ -688,7 +488,8 @@ public interface DeviceManagementService {
                             response = ErrorResponse.class),
                     @ApiResponse(
                             code = 404,
-                            message = "Not Found. \n Device of which the operation list is requested, is not found."),
+                            message = "Not Found. \n Device of which the operation list is requested, is not found.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 406,
                             message = "Not Acceptable. \n The requested media type is not supported."),
@@ -775,7 +576,8 @@ public interface DeviceManagementService {
                             response = ErrorResponse.class),
                     @ApiResponse(
                             code = 404,
-                            message = "Not Found. \n Device of which the effective policy is requested, is not found."),
+                            message = "Not Found. \n Device of which the effective policy is requested, is not found.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 406,
                             message = "Not Acceptable. \n The requested media type is not supported."),
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/NotificationManagementService.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/NotificationManagementService.java
index bdd7307196..6a21547885 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/NotificationManagementService.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/NotificationManagementService.java
@@ -71,6 +71,15 @@ public interface NotificationManagementService {
                     @ApiResponse(
                             code = 304,
                             message = "Not Modified. \n Empty body because the client has already the latest version of the requested resource."),
+                    @ApiResponse(
+                            code = 400,
+                            message = "Bad Request. \n Invalid notification status type " +
+                                    "received. Valid status types are NEW | CHECKED",
+                            response = ErrorResponse.class),
+                    @ApiResponse(
+                            code = 404,
+                            message = "Not Found. \n No notification is available to be retrieved.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 406,
                             message = "Not Acceptable.\n The requested media type is not supported"),
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/PolicyManagementService.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/PolicyManagementService.java
index b4daa172bc..c1e268eb7f 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/PolicyManagementService.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/PolicyManagementService.java
@@ -20,6 +20,7 @@ package org.wso2.carbon.device.mgt.jaxrs.service.api;
 
 import io.swagger.annotations.*;
 import org.wso2.carbon.apimgt.annotations.api.Permission;
+import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
 import org.wso2.carbon.device.mgt.jaxrs.beans.PolicyWrapper;
 import org.wso2.carbon.policy.mgt.common.Policy;
 
@@ -66,7 +67,8 @@ public interface PolicyManagementService {
                                     @ResponseHeader(
                                             name = "Last-Modified",
                                             description = "Date and time the resource has been modified the last time.\n" +
-                                                    "Used by caches, or in conditional requests.")}),
+                                                    "Used by caches, or in conditional requests.")
+                            }),
                     @ApiResponse(
                             code = 303,
                             message = "See Other. \n Source can be retrieved from the URL specified at the Location header.",
@@ -76,14 +78,21 @@ public interface PolicyManagementService {
                                             description = "The Source URL of the document.")}),
                     @ApiResponse(
                             code = 400,
-                            message = "Bad Request. \n Invalid request or validation error."),
+                            message = "Bad Request. \n Invalid request or validation error.",
+                            response = ErrorResponse.class),
+                    @ApiResponse(
+                            code = 401,
+                            message = "Not Found. \n Current logged in user is not authorized to add policies.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 415,
                             message = "Unsupported media type. \n The entity of the request was in a not supported format."),
                     @ApiResponse(
                             code = 500,
                             message = "Internal Server ErrorResponse. \n " +
-                                    "Server error occurred while adding a new policy.")})
+                                    "Server error occurred while adding a new policy.",
+                            response = ErrorResponse.class)
+            })
     @Permission(scope = "policy-modify", permissions = {"/permission/admin/device-mgt/admin/policies/add"})
     Response addPolicy(
             @ApiParam(
@@ -123,12 +132,18 @@ public interface PolicyManagementService {
                     @ApiResponse(
                             code = 304,
                             message = "Not Modified. \n Empty body because the client has already the latest version of the requested resource."),
+                    @ApiResponse(
+                            code = 400,
+                            message = "Bad Request. \n Invalid request or validation error.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 406,
                             message = "Not Acceptable.\n The requested media type is not supported"),
                     @ApiResponse(
                             code = 500,
-                            message = "Internal Server ErrorResponse. \n Server error occurred while fetching policies.")
+                            message = ("Internal Server ErrorResponse. \n Server error occurred while fetching " +
+                                    "policies."),
+                            response = ErrorResponse.class)
             })
     @Permission(scope = "policy-view", permissions = {"/permission/admin/device-mgt/admin/policies/list"})
     Response getPolicies(
@@ -181,13 +196,17 @@ public interface PolicyManagementService {
                             message = "Not Modified. \n Empty body because the client has already the latest version of the requested resource."),
                     @ApiResponse(
                             code = 404,
-                            message = "Not Found. \n No policy is found with the given id."),
+                            message = "Not Found. \n No policy is found with the given id.",
+                            response = ErrorResponse.class
+                    ),
                     @ApiResponse(
                             code = 406,
                             message = "Not Acceptable.\n The requested media type is not supported"),
                     @ApiResponse(
                             code = 500,
-                            message = "Internal Server ErrorResponse. \n Server error occurred while fetching the policy.")
+                            message = "Internal Server ErrorResponse. \n Server error occurred while fetching the " +
+                                    "policy.",
+                            response = ErrorResponse.class)
             })
     @Permission(scope = "policy-view", permissions = {"/permission/admin/device-mgt/admin/policies/list"})
     Response getPolicy(
@@ -234,17 +253,20 @@ public interface PolicyManagementService {
                                                     "Used by caches, or in conditional requests.")}),
                     @ApiResponse(
                             code = 400,
-                            message = "Bad Request. \n Invalid request or validation error."),
+                            message = "Bad Request. \n Invalid request or validation error.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 404,
-                            message = "Not Found. \n Resource to be deleted does not exist."),
+                            message = "Not Found. \n Resource to be deleted does not exist.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 415,
                             message = "Unsupported media type. \n The entity of the request was in a not supported format."),
                     @ApiResponse(
                             code = 500,
                             message = "Internal Server ErrorResponse. \n " +
-                                    "Server error occurred while updating the policy.")
+                                    "Server error occurred while updating the policy.",
+                            response = ErrorResponse.class)
             })
     @Permission(scope = "policy-modify", permissions = {"/permission/admin/device-mgt/admin/policies/update"})
     Response updatePolicy(
@@ -273,17 +295,20 @@ public interface PolicyManagementService {
                             message = "OK. \n Policies have successfully been removed"),
                     @ApiResponse(
                             code = 400,
-                            message = "Bad Request. \n Invalid request or validation error."),
+                            message = "Bad Request. \n Invalid request or validation error.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 404,
-                            message = "Not Found. \n Resource to be deleted does not exist."),
+                            message = "Not Found. \n Resource to be deleted does not exist.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 415,
                             message = "Unsupported media type. \n The entity of the request was in a not supported format."),
                     @ApiResponse(
                             code = 500,
                             message = "Internal Server ErrorResponse. \n " +
-                                    "Server error occurred while bulk removing policies.")
+                                    "Server error occurred while bulk removing policies.",
+                            response = ErrorResponse.class)
             })
     @Permission(scope = "policy-modify", permissions = {"/permission/admin/device-mgt/admin/policies/remove"})
     Response removePolicies(
@@ -304,8 +329,21 @@ public interface PolicyManagementService {
             tags = "Device Policy Management")
     @ApiResponses(
             value = {
-                    @ApiResponse(code = 200, message = "Policies have been successfully activated."),
-                    @ApiResponse(code = 500, message = "ErrorResponse in activating policies.")
+                    @ApiResponse(
+                            code = 200,
+                            message = "Policies have been successfully activated."),
+                    @ApiResponse(
+                            code = 400,
+                            message = "Bad Request. \n Invalid request or validation error.",
+                            response = ErrorResponse.class),
+                    @ApiResponse(
+                            code = 404,
+                            message = "Not Found. \n Resource does not exist.",
+                            response = ErrorResponse.class),
+                    @ApiResponse(
+                            code = 500,
+                            message = "ErrorResponse in activating policies.",
+                            response = ErrorResponse.class)
             })
     @Permission(scope = "policy-modify", permissions = {
             "/permission/admin/device-mgt/admin/policies/update",
@@ -325,8 +363,21 @@ public interface PolicyManagementService {
                     "is in the active state to the inactive state.",
             tags = "Device Policy Management")
     @ApiResponses(value = {
-            @ApiResponse(code = 200, message = "Policies have been successfully deactivated."),
-            @ApiResponse(code = 500, message = "ErrorResponse in deactivating policies.")
+            @ApiResponse(
+                    code = 200,
+                    message = "Policies have been successfully deactivated."),
+            @ApiResponse(
+                    code = 400,
+                    message = "Bad Request. \n Invalid request or validation error.",
+                    response = ErrorResponse.class),
+            @ApiResponse(
+                    code = 404,
+                    message = "Not Found. \n Resource does not exist.",
+                    response = ErrorResponse.class),
+            @ApiResponse(
+                    code = 500,
+                    message = "ErrorResponse in deactivating policies.",
+                    response = ErrorResponse.class)
     })
     @Permission(scope = "policy-modify", permissions = {
             "/permission/admin/device-mgt/admin/policies/update",
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/RoleManagementService.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/RoleManagementService.java
index 1785d92b82..06f52e1dda 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/RoleManagementService.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/RoleManagementService.java
@@ -70,6 +70,10 @@ public interface RoleManagementService {
                     @ApiResponse(
                             code = 304,
                             message = "Not Modified. \n Empty body because the client has already the latest version of the requested resource."),
+                    @ApiResponse(
+                            code = 404,
+                            message = "Not Found. \n Resource does not exist.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 406,
                             message = "Not Acceptable.\n The requested media type is not supported"),
@@ -147,9 +151,14 @@ public interface RoleManagementService {
                     @ApiResponse(
                             code = 304,
                             message = "Not Modified. \n Empty body because the client has already the latest version of the requested resource."),
+                    @ApiResponse(
+                            code = 400,
+                            message = "Bad Request. \n Invalid request or validation error.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 404,
-                            message = "Not Found. \n Resource to be deleted does not exist."),
+                            message = "Not Found. \n Resource does not exist.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 406,
                             message = "Not Acceptable.\n The requested media type is not supported"),
@@ -201,16 +210,23 @@ public interface RoleManagementService {
                             }),
                     @ApiResponse(
                             code = 304,
-                            message = "Not Modified. \n Empty body because the client has already the latest version of the requested resource."),
+                            message = "Not Modified. \n Empty body because the client has already the latest version of" +
+                                    " the requested resource."),
+                    @ApiResponse(
+                            code = 400,
+                            message = "Bad Request. \n Invalid request or validation error.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 404,
-                            message = "Not Found. \n Resource to be deleted does not exist."),
+                            message = "Not Found. \n Resource does not exist.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 406,
                             message = "Not Acceptable.\n The requested media type is not supported"),
                     @ApiResponse(
                             code = 500,
-                            message = "Internal Server ErrorResponse. \n Server error occurred while fetching the requested role.",
+                            message = "Internal Server ErrorResponse. \n Server error occurred while fetching the " +
+                                    "requested role.",
                             response = ErrorResponse.class)
     })
     @Permission(scope = "roles-view", permissions = {"/permission/admin/device-mgt/admin/roles/list"})
@@ -349,6 +365,10 @@ public interface RoleManagementService {
             @ApiResponse(
                     code = 200,
                     message = "OK. \n Role has successfully been removed"),
+            @ApiResponse(
+                    code = 400,
+                    message = "Bad Request. \n Invalid request or validation error.",
+                    response = ErrorResponse.class),
             @ApiResponse(
                     code = 404,
                     message = "Not Found. \n Resource to be deleted does not exist."),
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/UserManagementService.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/UserManagementService.java
index a9285d47ce..89ac39b3eb 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/UserManagementService.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/UserManagementService.java
@@ -21,6 +21,7 @@ package org.wso2.carbon.device.mgt.jaxrs.service.api;
 import io.swagger.annotations.*;
 import org.wso2.carbon.apimgt.annotations.api.API;
 import org.wso2.carbon.apimgt.annotations.api.Permission;
+import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
 import org.wso2.carbon.device.mgt.jaxrs.beans.OldPasswordResetWrapper;
 import org.wso2.carbon.device.mgt.jaxrs.beans.UserList;
 import org.wso2.carbon.device.mgt.jaxrs.beans.UserWrapper;
@@ -76,13 +77,18 @@ public interface UserManagementService {
                     @ApiResponse(
                             code = 400,
                             message = "Bad Request. \n Invalid request or validation error."),
+                    @ApiResponse(
+                            code = 409,
+                            message = "Conflict. \n User already exist.",
+                            response = ErrorResponse.class),
                     @ApiResponse(
                             code = 415,
                             message = "Unsupported media type. \n The entity of the request was in a not supported format."),
                     @ApiResponse(
                             code = 500,
                             message = "Internal Server ErrorResponse. \n " +
-                                    "Server error occurred while adding a new user.")
+                                    "Server error occurred while adding a new user.",
+                            response = ErrorResponse.class)
             })
     @Permission(scope = "user-modify", permissions = {"/permission/admin/device-mgt/admin/user/add"})
     Response addUser(
@@ -124,13 +130,16 @@ public interface UserManagementService {
                     message = "Not Modified. \n Empty body because the client has already the latest version of the requested resource."),
             @ApiResponse(
                     code = 404,
-                    message = "Not Found. \n Resource to be deleted does not exist."),
+                    message = "Not Found. \n Resource does not exist.",
+                    response = ErrorResponse.class),
             @ApiResponse(
                     code = 406,
                     message = "Not Acceptable.\n The requested media type is not supported"),
             @ApiResponse(
                     code = 500,
-                    message = "Internal Server ErrorResponse. \n Server error occurred while fetching the requested user.")
+                    message = "Internal Server ErrorResponse. \n Server error occurred while" +
+                            " fetching the requested user.",
+                    response = ErrorResponse.class)
     })
     @Permission(scope = "user-view", permissions = {"/permission/admin/device-mgt/admin/user/view"})
     Response getUser(
@@ -179,14 +188,16 @@ public interface UserManagementService {
                     message = "Bad Request. \n Invalid request or validation error."),
             @ApiResponse(
                     code = 404,
-                    message = "Not Found. \n Resource to be deleted does not exist."),
+                    message = "Not Found. \n Resource does not exist.",
+                    response = ErrorResponse.class),
             @ApiResponse(
                     code = 415,
                     message = "Unsupported media type. \n The entity of the request was in a not supported format."),
             @ApiResponse(
                     code = 500,
                     message = "Internal Server ErrorResponse. \n " +
-                            "Server error occurred while updating the user.")
+                            "Server error occurred while updating the user.",
+                    response = ErrorResponse.class)
     })
     @Permission(scope = "user-modify", permissions = {"/permission/admin/device-mgt/admin/user/update"})
     Response updateUser(
@@ -214,11 +225,14 @@ public interface UserManagementService {
                     message = "OK. \n User has successfully been removed"),
             @ApiResponse(
                     code = 404,
-                    message = "Not Found. \n Resource to be deleted does not exist."),
+                    message = "Not Found. \n Resource to be deleted does not exist.",
+                    response = ErrorResponse.class),
             @ApiResponse(
                     code = 500,
                     message = "Internal Server ErrorResponse. \n " +
-                            "Server error occurred while removing the user.")
+                            "Server error occurred while removing the user.",
+                    response = ErrorResponse.class
+            )
     })
     @Permission(scope = "user-modify", permissions = {"/permission/admin/device-mgt/admin/user/remove"})
     Response removeUser(
@@ -260,13 +274,16 @@ public interface UserManagementService {
                     message = "Not Modified. \n Empty body because the client has already the latest version of the requested resource."),
             @ApiResponse(
                     code = 404,
-                    message = "Not Found. \n Resource to be deleted does not exist."),
+                    message = "Not Found. \n Resource to be deleted does not exist.",
+                    response = ErrorResponse.class),
             @ApiResponse(
                     code = 406,
                     message = "Not Acceptable.\n The requested media type is not supported"),
             @ApiResponse(
                     code = 500,
-                    message = "Internal Server ErrorResponse. \n Server error occurred while fetching the role list assigned to the user.")
+                    message = "Internal Server ErrorResponse. \n Server error occurred while fetching the role list" +
+                            " assigned to the user.",
+                    response = ErrorResponse.class)
     })
     @Permission(scope = "user-view", permissions = {"/permission/admin/device-mgt/admin/user/view"})
     Response getRolesOfUser(
@@ -310,7 +327,8 @@ public interface UserManagementService {
                     message = "Not Acceptable.\n The requested media type is not supported"),
             @ApiResponse(
                     code = 500,
-                    message = "Internal Server ErrorResponse. \n Server error occurred while fetching the user list.")
+                    message = "Internal Server ErrorResponse. \n Server error occurred while fetching the user list.",
+                    response = ErrorResponse.class)
     })
     @Permission(scope = "user-view", permissions = {"/permission/admin/device-mgt/admin/user/list"})
     Response getUsers(
@@ -376,7 +394,9 @@ public interface UserManagementService {
                     message = "Not Acceptable.\n The requested media type is not supported"),
             @ApiResponse(
                     code = 500,
-                    message = "Internal Server ErrorResponse. \n Server error occurred while fetching the username list that matches the given filter.")
+                    message = "Internal Server ErrorResponse. \n Server error occurred while fetching the username " +
+                            "list that matches the given filter.",
+                    response = ErrorResponse.class)
     })
     @Permission(scope = "user-view", permissions = {"/permission/admin/device-mgt/admin/user/list"})
     Response getUserNames(
@@ -416,7 +436,8 @@ public interface UserManagementService {
                     message = "OK. \n Credentials of the user have been updated successfully"),
             @ApiResponse(
                     code = 400,
-                    message = "Bad Request. \n Invalid request or validation error."),
+                    message = "Bad Request. \n Invalid request or validation error.",
+                    response = ErrorResponse.class),
             @ApiResponse(
                     code = 404,
                     message = "Not Found. \n Resource to be deleted does not exist."),
@@ -426,7 +447,8 @@ public interface UserManagementService {
             @ApiResponse(
                     code = 500,
                     message = "Internal Server ErrorResponse. \n " +
-                            "Server error occurred while updating credentials of the user.")
+                            "Server error occurred while updating credentials of the user.",
+                    response = ErrorResponse.class)
     })
     @Permission(scope = "user-modify", permissions = {"/permission/admin/login"})
     Response resetPassword(
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/admin/DeviceManagementAdminService.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/admin/DeviceManagementAdminService.java
index 2ed4403b68..2396de53f1 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/admin/DeviceManagementAdminService.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/admin/DeviceManagementAdminService.java
@@ -21,6 +21,7 @@ package org.wso2.carbon.device.mgt.jaxrs.service.api.admin;
 import io.swagger.annotations.*;
 import org.wso2.carbon.apimgt.annotations.api.API;
 import org.wso2.carbon.device.mgt.common.Device;
+import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
 
 import javax.ws.rs.*;
 import javax.ws.rs.core.MediaType;
@@ -64,16 +65,23 @@ public interface DeviceManagementAdminService {
                     }),
             @ApiResponse(
                     code = 304,
-                    message = "Not Modified. \n Empty body because the client has already the latest version of the requested resource."),
+                    message = "Not Modified. \n Empty body because the client has already the latest version of " +
+                            "the requested resource."),
             @ApiResponse(
                     code = 401,
-                    message = "Unauthorized.\n The requested resource access is unauthorized"),
+                    message = "Unauthorized.\n The requested resource access is unauthorized",
+                    response = ErrorResponse.class),
+            @ApiResponse(
+                    code = 404,
+                    message = "Not Found.\n No device found that matches the given name.",
+                    response = ErrorResponse.class),
             @ApiResponse(
                     code = 406,
                     message = "Not Acceptable.\n The requested media type is not supported"),
             @ApiResponse(
                     code = 500,
-                    message = "Internal Server ErrorResponse. \n Server error occurred while fetching the device list.")
+                    message = "Internal Server ErrorResponse. \n Server error occurred while fetching the device list.",
+                    response = ErrorResponse.class)
     })
     Response getDevicesByName(
             @ApiParam(
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/admin/UserManagementAdminService.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/admin/UserManagementAdminService.java
index d44bd57f77..fb8610ce43 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/admin/UserManagementAdminService.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/admin/UserManagementAdminService.java
@@ -20,6 +20,7 @@ package org.wso2.carbon.device.mgt.jaxrs.service.api.admin;
 
 import io.swagger.annotations.*;
 import org.wso2.carbon.apimgt.annotations.api.Permission;
+import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
 import org.wso2.carbon.device.mgt.jaxrs.beans.PasswordResetWrapper;
 
 import javax.ws.rs.*;
@@ -49,7 +50,8 @@ public interface UserManagementAdminService {
                     message = "OK. \n Credentials of the user have been updated successfully"),
             @ApiResponse(
                     code = 400,
-                    message = "Bad Request. \n Invalid request or validation error."),
+                    message = "Bad Request. \n Invalid request or validation error.",
+                    response = ErrorResponse.class),
             @ApiResponse(
                     code = 404,
                     message = "Not Found. \n Resource to be deleted does not exist."),
@@ -59,7 +61,8 @@ public interface UserManagementAdminService {
             @ApiResponse(
                     code = 500,
                     message = "Internal Server ErrorResponse. \n " +
-                            "Server error occurred while updating credentials of the user.")
+                            "Server error occurred while updating credentials of the user.",
+                    response = ErrorResponse.class)
     })
     @Permission(scope = "user-modify", permissions = {"/permission/admin/login"})
     Response resetUserPassword(
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/ActivityProviderServiceImpl.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/ActivityProviderServiceImpl.java
index c5f2fb728c..f351d38e88 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/ActivityProviderServiceImpl.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/ActivityProviderServiceImpl.java
@@ -25,8 +25,8 @@ import org.wso2.carbon.device.mgt.common.operation.mgt.OperationManagementExcept
 import org.wso2.carbon.device.mgt.core.service.DeviceManagementProviderService;
 import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
 import org.wso2.carbon.device.mgt.jaxrs.service.api.ActivityInfoProviderService;
-import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.RequestValidationUtil;
-import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.UnexpectedServerErrorException;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.*;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.NotFoundException;
 import org.wso2.carbon.device.mgt.jaxrs.util.DeviceMgtAPIUtils;
 
 import javax.ws.rs.*;
@@ -55,8 +55,9 @@ public class ActivityProviderServiceImpl implements ActivityInfoProviderService
             dmService = DeviceMgtAPIUtils.getDeviceManagementService();
             activity = dmService.getOperationByActivityId(id);
             if (activity == null) {
-                return Response.status(Response.Status.NOT_FOUND).entity("No activity can be found upon the provided " +
-                        "activity id '" + id + "'").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("No activity can be " +
+                                "found upon the provided activity id '" + id + "'").build());
             }
         } catch (OperationManagementException e) {
             String msg = "ErrorResponse occurred while fetching the activity for the supplied id.";
@@ -71,14 +72,18 @@ public class ActivityProviderServiceImpl implements ActivityInfoProviderService
     @Override
     public Response getActivities(
             @QueryParam("timestamp") long timestamp,
-            @HeaderParam("If-Modified-Since") String ifModifiedSince,
             @QueryParam("offset") int offset,
             @QueryParam("limit") int limit) {
-        List<Activity> activities = null;
+        List<Activity> activities;
         DeviceManagementProviderService dmService;
         try {
             dmService = DeviceMgtAPIUtils.getDeviceManagementService();
             activities = dmService.getActivitiesUpdatedAfter(timestamp);
+            if (activities == null || activities.size() == 0) {
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("No activities " +
+                                "found.").build());
+            }
 
         } catch (OperationManagementException e) {
             String msg = "ErrorResponse occurred while fetching the activities updated after given time stamp.";
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/ConfigurationServiceImpl.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/ConfigurationServiceImpl.java
index 4a2126f6aa..4cde53bad1 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/ConfigurationServiceImpl.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/ConfigurationServiceImpl.java
@@ -25,6 +25,7 @@ import org.wso2.carbon.device.mgt.common.configuration.mgt.ConfigurationManageme
 import org.wso2.carbon.device.mgt.common.configuration.mgt.PlatformConfiguration;
 import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
 import org.wso2.carbon.device.mgt.jaxrs.service.api.ConfigurationManagementService;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.RequestValidationUtil;
 import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.UnexpectedServerErrorException;
 import org.wso2.carbon.device.mgt.jaxrs.util.DeviceMgtAPIUtils;
 import org.wso2.carbon.device.mgt.jaxrs.util.MDMAppConstants;
@@ -74,6 +75,7 @@ public class ConfigurationServiceImpl implements ConfigurationManagementService
     @Override
     public Response updateConfiguration(PlatformConfiguration config) {
         try {
+            RequestValidationUtil.validateUpdateConfiguration(config);
             DeviceMgtAPIUtils.getPlatformConfigurationManagementService().saveConfiguration(config,
                     MDMAppConstants.RegistryConstants.GENERAL_CONFIG_RESOURCE_PATH);
             //Schedule the task service
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/DeviceManagementServiceImpl.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/DeviceManagementServiceImpl.java
index 5ad347241c..e641efcac7 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/DeviceManagementServiceImpl.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/DeviceManagementServiceImpl.java
@@ -38,8 +38,8 @@ import org.wso2.carbon.device.mgt.core.service.DeviceManagementProviderService;
 import org.wso2.carbon.device.mgt.jaxrs.beans.DeviceList;
 import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
 import org.wso2.carbon.device.mgt.jaxrs.service.api.DeviceManagementService;
-import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.RequestValidationUtil;
-import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.UnexpectedServerErrorException;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.*;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.NotFoundException;
 import org.wso2.carbon.device.mgt.jaxrs.util.DeviceMgtAPIUtils;
 import org.wso2.carbon.policy.mgt.common.Policy;
 import org.wso2.carbon.policy.mgt.common.PolicyManagementException;
@@ -94,8 +94,9 @@ public class DeviceManagementServiceImpl implements DeviceManagementService {
                 result = dms.getAllDevices(request);
             }
             if (result == null) {
-                return Response.status(Response.Status.NOT_FOUND).entity("No device is currently enrolled " +
-                        "with the server").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("No device is currently" +
+                                " enrolled with the server").build());
             }
             DeviceList devices = new DeviceList();
             devices.setList((List<Device>) result.getData());
@@ -109,56 +110,6 @@ public class DeviceManagementServiceImpl implements DeviceManagementService {
         }
     }
 
-//    @GET
-//    @Path("{type}/{id}/info")
-//    public Response getDeviceInfo(@PathParam("type") String type, @NotNull @PathParam("id") String id,
-//                                  @HeaderParam("If-Modified-Since") String timestamp) {
-//        DeviceInformationManager informationManager;
-//        DeviceInfo deviceInfo;
-//        try {
-//            RequestValidationUtil.validateDeviceIdentifier(type, id);
-//
-//            DeviceIdentifier deviceIdentifier = new DeviceIdentifier();
-//            deviceIdentifier.setId(id);
-//            deviceIdentifier.setType(type);
-//            informationManager = DeviceMgtAPIUtils.getDeviceInformationManagerService();
-//            deviceInfo = informationManager.getDeviceInfo(deviceIdentifier);
-//            if (deviceInfo == null) {
-//                return Response.status(Response.Status.NOT_FOUND).entity("It is likely that no device is " +
-//                        "found upon the give type '" + type + "' and id '" + id + "'").build();
-//            }
-//        } catch (DeviceDetailsMgtException e) {
-//            String msg = "Error occurred while getting the device information.";
-//            log.error(msg, e);
-//            throw new UnexpectedServerErrorException(
-//                    new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
-//        }
-//        return Response.status(Response.Status.OK).entity(deviceInfo).build();
-//    }
-
-//    @POST
-//    @Path("/get-info")
-//    @Override
-//    public Response getDevicesInfo(
-//            @HeaderParam("If-Modified-Since") String timestamp,
-//            List<DeviceIdentifier> deviceIds) {
-//        DeviceInformationManager informationManager;
-//        List<DeviceInfo> deviceInfo;
-//        try {
-//            informationManager = DeviceMgtAPIUtils.getDeviceInformationManagerService();
-//            deviceInfo = informationManager.getDevicesInfo(deviceIds);
-//            if (deviceInfo == null) {
-//                return Response.status(Response.Status.NOT_FOUND).entity("No device information is available for the " +
-//                        "device list submitted").build();
-//            }
-//        } catch (DeviceDetailsMgtException e) {
-//            String msg = "Error occurred while getting the device information.";
-//            log.error(msg, e);
-//            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(msg).build();
-//        }
-//        return Response.status(Response.Status.OK).entity(deviceInfo).build();
-//    }
-
     @GET
     @Path("/{type}/{id}")
     @Override
@@ -179,59 +130,13 @@ public class DeviceManagementServiceImpl implements DeviceManagementService {
                     new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
         }
         if (device == null) {
-            return Response.status(Response.Status.NOT_FOUND).entity("Requested device of type '" + type +
-                    "', which carries id '" + id + "' does not exist").build();
+            throw new NotFoundException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("Requested device of type '" +
+                            type + "', which carries id '" + id + "' does not exist").build());
         }
         return Response.status(Response.Status.OK).entity(device).build();
     }
 
-//    @GET
-//    @Path("/{type}/{id}/location")
-//    //@Override
-//    public Response getDeviceLocation(
-//            @PathParam("type") String type,
-//            @PathParam("id") String id,
-//            @HeaderParam("If-Modified-Since") String ifModifiedSince) {
-//        DeviceInformationManager informationManager;
-//        DeviceLocation deviceLocation;
-//        try {
-//            RequestValidationUtil.validateDeviceIdentifier(type, id);
-//
-//            informationManager = DeviceMgtAPIUtils.getDeviceInformationManagerService();
-//            deviceLocation = informationManager.getDeviceLocation(new DeviceIdentifier(id, type));
-//            if (deviceLocation == null || deviceLocation.getLatitude() == null ||
-//                    deviceLocation.getLongitude() == null) {
-//                return Response.status(Response.Status.NOT_FOUND).entity("Location details are not available for the " +
-//                        "given device id '" + id + "'").build();
-//            }
-//        } catch (DeviceDetailsMgtException e) {
-//            String msg = "Error occurred while getting the last updated location of the '" + type + "' device, " +
-//                    "which carries the id '" + id + "'";
-//            log.error(msg, e);
-//            throw new UnexpectedServerErrorException(
-//                    new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
-//        }
-//        return Response.status(Response.Status.OK).entity(deviceLocation).build();
-//    }
-
-//    @POST
-//    @Path("/locations")
-//    public Response getDeviceLocations(List<DeviceIdentifier> deviceIdentifiers,
-//                                       @HeaderParam("If-Modified-Since") String ifModifiedSince) {
-//        DeviceInformationManager informationManager;
-//        List<DeviceLocation> deviceLocations;
-//        try {
-//            informationManager = DeviceMgtAPIUtils.getDeviceInformationManagerService();
-//            deviceLocations = informationManager.getDeviceLocations(deviceIdentifiers);
-//        } catch (DeviceDetailsMgtException e) {
-//            String msg = "Error occurred while getting the device location.";
-//            log.error(msg, e);
-//            throw new UnexpectedServerErrorException(
-//                    new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
-//        }
-//        return Response.status(Response.Status.OK).entity(deviceLocations).build();
-//    }
-
     @GET
     @Path("/{type}/{id}/features")
     @Override
@@ -247,8 +152,9 @@ public class DeviceManagementServiceImpl implements DeviceManagementService {
             dms = DeviceMgtAPIUtils.getDeviceManagementService();
             FeatureManager fm = dms.getFeatureManager(type);
             if (fm == null) {
-                return Response.status(Response.Status.NOT_FOUND).entity("No feature manager is registered with " +
-                        "the given type '" + type + "'").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("No feature manager is " +
+                                "registered with the given type '" + type + "'").build());
             }
             features = fm.getFeatures();
         } catch (DeviceManagementException e) {
@@ -278,10 +184,10 @@ public class DeviceManagementServiceImpl implements DeviceManagementService {
                     new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
         }
         if (devices == null || devices.size() == 0) {
-            return Response.status(Response.Status.NOT_FOUND).entity("It is likely that no device is found upon " +
-                "the provided search filters").build();
+            throw new NotFoundException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("It is likely that no device is found upon " +
+                            "the provided search filters").build());
         }
-
         return Response.status(Response.Status.OK).entity(devices).build();
     }
 
@@ -302,8 +208,9 @@ public class DeviceManagementServiceImpl implements DeviceManagementService {
             amc = DeviceMgtAPIUtils.getAppManagementService();
             applications = amc.getApplicationListForDevice(new DeviceIdentifier(id, type));
             if (applications == null) {
-                return Response.status(Response.Status.NOT_FOUND).entity("It is likely that no device is found upon" +
-                        " the provided type and id").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("It is likely that " +
+                                "no applications is found upon the provided type and id").build());
             }
         } catch (ApplicationManagementException e) {
             String msg = "Error occurred while fetching the apps of the '" + type + "' device, which carries " +
@@ -332,8 +239,9 @@ public class DeviceManagementServiceImpl implements DeviceManagementService {
             dms = DeviceMgtAPIUtils.getDeviceManagementService();
             operations = dms.getOperations(new DeviceIdentifier(id, type));
             if (operations == null) {
-                return Response.status(Response.Status.NOT_FOUND).entity("It is likely that no device is found upon " +
-                        "the provided type and id").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("It is likely that" +
+                                " no operation is found upon the provided type and id").build());
             }
         } catch (OperationManagementException e) {
             String msg = "Error occurred while fetching the operations for the '" + type + "' device, which " +
@@ -357,8 +265,9 @@ public class DeviceManagementServiceImpl implements DeviceManagementService {
             PolicyManagerService policyManagementService = DeviceMgtAPIUtils.getPolicyManagementService();
             Policy policy = policyManagementService.getAppliedPolicyToDevice(new DeviceIdentifier(id, type));
             if (policy == null) {
-                return Response.status(Response.Status.NOT_FOUND).entity("No policy has been found for the '" +
-                        type + "' device, which carries the id '" + id + "'").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("No policy has " +
+                                "been found for the '" + type + "' device, which carries the id '" + id + "'").build());
             }
             return Response.status(Response.Status.OK).entity(policy).build();
         } catch (PolicyManagementException e) {
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/NotificationManagementServiceImpl.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/NotificationManagementServiceImpl.java
index 077996f0b7..8d7a2a72b1 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/NotificationManagementServiceImpl.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/NotificationManagementServiceImpl.java
@@ -25,8 +25,8 @@ import org.wso2.carbon.device.mgt.common.notification.mgt.NotificationManagement
 import org.wso2.carbon.device.mgt.jaxrs.NotificationContext;
 import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
 import org.wso2.carbon.device.mgt.jaxrs.service.api.NotificationManagementService;
-import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.RequestValidationUtil;
-import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.UnexpectedServerErrorException;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.*;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.NotFoundException;
 import org.wso2.carbon.device.mgt.jaxrs.util.DeviceMgtAPIUtils;
 
 import javax.ws.rs.*;
@@ -59,9 +59,10 @@ public class NotificationManagementServiceImpl implements NotificationManagement
                 notifications = DeviceMgtAPIUtils.getNotificationManagementService().getAllNotifications();
             }
 
-            if (notifications == null) {
-                return Response.status(Response.Status.NOT_FOUND).entity("No notification is available to be " +
-                        "retrieved").build();
+            if (notifications == null || notifications.size() == 0) {
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("No notification is " +
+                                "available to be retrieved.").build());
             }
             return Response.status(Response.Status.OK).entity(notifications).build();
         } catch (NotificationManagementException e) {
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/PolicyManagementServiceImpl.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/PolicyManagementServiceImpl.java
index aeacd9046e..520285fe57 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/PolicyManagementServiceImpl.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/PolicyManagementServiceImpl.java
@@ -27,9 +27,12 @@ import org.wso2.carbon.device.mgt.common.DeviceManagementException;
 import org.wso2.carbon.device.mgt.common.authorization.DeviceAccessAuthorizationException;
 import org.wso2.carbon.device.mgt.common.authorization.DeviceAccessAuthorizationService;
 import org.wso2.carbon.device.mgt.core.internal.DeviceManagementDataHolder;
-import org.wso2.carbon.device.mgt.jaxrs.beans.PolicyList;
+import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
 import org.wso2.carbon.device.mgt.jaxrs.beans.PolicyWrapper;
 import org.wso2.carbon.device.mgt.jaxrs.service.api.PolicyManagementService;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.*;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.NotFoundException;
+import org.wso2.carbon.device.mgt.jaxrs.beans.PolicyList;
 import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.FilteringUtil;
 import org.wso2.carbon.device.mgt.jaxrs.util.DeviceMgtAPIUtils;
 import org.wso2.carbon.device.mgt.jaxrs.util.DeviceMgtUtil;
@@ -53,7 +56,9 @@ public class PolicyManagementServiceImpl implements PolicyManagementService {
     @POST
     @Override
     public Response addPolicy(PolicyWrapper policyWrapper) {
+        RequestValidationUtil.validatePolicyDetails(policyWrapper);
         PolicyManagerService policyManagementService = DeviceMgtAPIUtils.getPolicyManagementService();
+
         try {
             Policy policy = this.getPolicyFromWrapper(policyWrapper);
 
@@ -67,13 +72,15 @@ public class PolicyManagementServiceImpl implements PolicyManagementService {
                 String username = threadLocalCarbonContext.getUsername();
                 try {
                     if (!deviceAccessAuthorizationService.isUserAuthorized(deviceIdentifier, username)) {
-                        return Response.status(Response.Status.UNAUTHORIZED).entity("Current logged in user is " +
-                                "not authorized to add policies").build();
+                        throw new UnauthorizedAccessException(
+                                new ErrorResponse.ErrorResponseBuilder().setCode(401l).setMessage
+                                        ("Current logged in user is not authorized to add policies").build());
                     }
                 } catch (DeviceAccessAuthorizationException e) {
                     String msg = "ErrorResponse occurred while checking if the current user is authorized to add a policy";
                     log.error(msg, e);
-                    return javax.ws.rs.core.Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(msg).build();
+                    throw new UnexpectedServerErrorException(
+                            new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
                 }
             }
 
@@ -83,11 +90,13 @@ public class PolicyManagementServiceImpl implements PolicyManagementService {
         } catch (PolicyManagementException e) {
             String msg = "ErrorResponse occurred while adding policy";
             log.error(msg, e);
-            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(msg).build();
+            throw new UnexpectedServerErrorException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
         } catch (DeviceManagementException e) {
             String msg = "ErrorResponse occurred while retrieving device list.";
             log.error(msg, e);
-            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(msg).build();
+            throw new UnexpectedServerErrorException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
         }
     }
 
@@ -127,7 +136,8 @@ public class PolicyManagementServiceImpl implements PolicyManagementService {
             PolicyAdministratorPoint policyAdministratorPoint = policyManagementService.getPAP();
             policies = policyAdministratorPoint.getPolicies();
             if (policies == null || policies.size() == 0) {
-                return Response.status(Response.Status.NOT_FOUND).entity("No policies found.").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("No policies found.").build());
             }
             targetPolicies.setCount(policies.size());
             filteredPolicies = FilteringUtil.getFilteredList(policies, offset, limit);
@@ -138,7 +148,8 @@ public class PolicyManagementServiceImpl implements PolicyManagementService {
         } catch (PolicyManagementException e) {
             String msg = "ErrorResponse occurred while retrieving all available policies";
             log.error(msg, e);
-            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(msg).build();
+            throw new UnexpectedServerErrorException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
         }
 
         return Response.status(Response.Status.OK).entity(targetPolicies).build();
@@ -154,12 +165,14 @@ public class PolicyManagementServiceImpl implements PolicyManagementService {
             PolicyAdministratorPoint policyAdministratorPoint = policyManagementService.getPAP();
             policy = policyAdministratorPoint.getPolicy(id);
             if (policy == null) {
-                return Response.status(Response.Status.NOT_FOUND).entity("Policy not found.").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("No policy found.").build());
             }
         } catch (PolicyManagementException e) {
             String msg = "ErrorResponse occurred while retrieving policy corresponding to the id '" + id + "'";
             log.error(msg, e);
-            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(msg).build();
+            throw new UnexpectedServerErrorException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
         }
         return Response.status(Response.Status.OK).entity(policy).build();
     }
@@ -168,6 +181,7 @@ public class PolicyManagementServiceImpl implements PolicyManagementService {
     @Path("/{id}")
     @Override
     public Response updatePolicy(@PathParam("id") int id, PolicyWrapper policyWrapper) {
+        RequestValidationUtil.validatePolicyDetails(policyWrapper);
         PolicyManagerService policyManagementService = DeviceMgtAPIUtils.getPolicyManagementService();
         try {
             Policy policy = this.getPolicyFromWrapper(policyWrapper);
@@ -178,15 +192,17 @@ public class PolicyManagementServiceImpl implements PolicyManagementService {
                 return Response.status(Response.Status.NOT_FOUND).entity("Policy not found.").build();
             }
             pap.updatePolicy(policy);
-            return Response.status(Response.Status.OK).entity("Policy has successfully been updated").build();
+            return Response.status(Response.Status.OK).entity("Policy has successfully been updated.").build();
         } catch (PolicyManagementException e) {
             String msg = "ErrorResponse occurred while updating the policy";
             log.error(msg, e);
-            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(msg).build();
+            throw new UnexpectedServerErrorException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
         } catch (DeviceManagementException e) {
             String msg = "ErrorResponse occurred while retrieving the device list.";
             log.error(msg, e);
-            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(msg).build();
+            throw new UnexpectedServerErrorException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
         }
     }
 
@@ -194,6 +210,7 @@ public class PolicyManagementServiceImpl implements PolicyManagementService {
     @Path("/remove-policy")
     @Override
     public Response removePolicies(List<Integer> policyIds) {
+        RequestValidationUtil.validatePolicyIds(policyIds);
         PolicyManagerService policyManagementService = DeviceMgtAPIUtils.getPolicyManagementService();
         boolean policyDeleted = true;
         try {
@@ -207,13 +224,15 @@ public class PolicyManagementServiceImpl implements PolicyManagementService {
         } catch (PolicyManagementException e) {
             String msg = "ErrorResponse occurred while removing policies";
             log.error(msg, e);
-            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(msg).build();
+            throw new UnexpectedServerErrorException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
         }
         if (policyDeleted) {
             return Response.status(Response.Status.OK).entity("Policies have been successfully deleted").build();
         } else {
             //TODO:Check of this logic is correct
-            return Response.status(Response.Status.NOT_FOUND).entity("Policy doesn't exist").build();
+            throw new NotFoundException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("Policy doesn't exist").build());
         }
     }
 
@@ -221,6 +240,7 @@ public class PolicyManagementServiceImpl implements PolicyManagementService {
     @Path("/activate-policy")
     @Override
     public Response activatePolicies(List<Integer> policyIds) {
+        RequestValidationUtil.validatePolicyIds(policyIds);
         boolean isPolicyActivated = false;
         try {
             PolicyManagerService policyManagementService = DeviceMgtAPIUtils.getPolicyManagementService();
@@ -235,14 +255,16 @@ public class PolicyManagementServiceImpl implements PolicyManagementService {
         } catch (PolicyManagementException e) {
             String msg = "ErrorResponse occurred while activating policies";
             log.error(msg, e);
-            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(msg).build();
+            throw new UnexpectedServerErrorException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
         }
         if (isPolicyActivated) {
             return Response.status(Response.Status.OK).entity("Selected policies have been successfully activated")
                     .build();
         } else {
-            return Response.status(Response.Status.NOT_FOUND).entity("Selected policies have not been activated")
-                    .build();
+            throw new NotFoundException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("Selected policies have " +
+                            "not been activated").build());
         }
     }
 
@@ -250,6 +272,7 @@ public class PolicyManagementServiceImpl implements PolicyManagementService {
     @Path("/deactivate-policy")
     @Override
     public Response deactivatePolicies(List<Integer> policyIds) {
+        RequestValidationUtil.validatePolicyIds(policyIds);
         boolean isPolicyDeActivated = false;
         try {
             PolicyManagerService policyManagementService = DeviceMgtAPIUtils.getPolicyManagementService();
@@ -264,14 +287,16 @@ public class PolicyManagementServiceImpl implements PolicyManagementService {
         } catch (PolicyManagementException e) {
             String msg = "Exception in inactivating policies.";
             log.error(msg, e);
-            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(msg).build();
+            throw new UnexpectedServerErrorException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(500l).setMessage(msg).build());
         }
         if (isPolicyDeActivated) {
             return Response.status(Response.Status.OK).entity("Selected policies have been successfully " +
                                                                       "deactivated").build();
         } else {
-            return Response.status(Response.Status.NOT_FOUND).entity("Selected policies have not been deactivated")
-                    .build();
+            throw new NotFoundException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("Selected policies have " +
+                            "not been deactivated").build());
         }
     }
 
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/RoleManagementServiceImpl.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/RoleManagementServiceImpl.java
index 46d4888ef2..620808a8f3 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/RoleManagementServiceImpl.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/RoleManagementServiceImpl.java
@@ -23,15 +23,16 @@ import org.apache.commons.logging.LogFactory;
 import org.wso2.carbon.CarbonConstants;
 import org.wso2.carbon.base.MultitenantConstants;
 import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
-import org.wso2.carbon.device.mgt.jaxrs.beans.RoleList;
 import org.wso2.carbon.device.mgt.jaxrs.service.api.RoleManagementService;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.*;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.NotFoundException;
+import org.wso2.carbon.device.mgt.jaxrs.beans.RoleList;
 import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.FilteringUtil;
 import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.UnexpectedServerErrorException;
 import org.wso2.carbon.device.mgt.jaxrs.util.DeviceMgtAPIUtils;
 import org.wso2.carbon.device.mgt.jaxrs.beans.RoleWrapper;
 import org.wso2.carbon.device.mgt.jaxrs.util.SetReferenceTransformer;
 import org.wso2.carbon.user.api.*;
-import org.wso2.carbon.user.core.common.AbstractUserStoreManager;
 import org.wso2.carbon.user.mgt.UserRealmProxy;
 import org.wso2.carbon.user.mgt.common.UIPermissionNode;
 import org.wso2.carbon.user.mgt.common.UserAdminException;
@@ -62,12 +63,14 @@ public class RoleManagementServiceImpl implements RoleManagementService {
         try {
             filteredRoles = getRolesFromUserStore();
             if (filteredRoles == null || filteredRoles.size() == 0) {
-                return Response.status(Response.Status.NOT_FOUND).entity("No roles found.").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("No roles found.").build());
             }
             targetRoles.setCount(filteredRoles.size());
             filteredRoles = FilteringUtil.getFilteredList(getRolesFromUserStore(), offset, limit);
             if (filteredRoles.size() == 0) {
-                return Response.status(Response.Status.NOT_FOUND).entity("No roles found.").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("No roles found").build());
             }
             targetRoles.setList(filteredRoles);
         } catch (UserStoreException e) {
@@ -85,6 +88,7 @@ public class RoleManagementServiceImpl implements RoleManagementService {
     public Response getPermissionsOfRole(
             @PathParam("roleName") String roleName,
             @HeaderParam("If-Modified-Since") String ifModifiedSince) {
+        RequestValidationUtil.validateRoleName(roleName);
         try {
             final UserRealm userRealm = DeviceMgtAPIUtils.getUserRealm();
             org.wso2.carbon.user.core.UserRealm userRealmCore = null;
@@ -95,8 +99,9 @@ public class RoleManagementServiceImpl implements RoleManagementService {
             final UserRealmProxy userRealmProxy = new UserRealmProxy(userRealmCore);
             rolePermissions = this.getUIPermissionNode(roleName, userRealmProxy);
             if (rolePermissions == null) {
-                return Response.status(Response.Status.NOT_FOUND).entity("No permissions found for the role '" +
-                        roleName + "'").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("No permissions found" +
+                                " for the role '" + roleName + "'").build());
             }
             return Response.status(Response.Status.OK).entity(rolePermissions).build();
         } catch (UserAdminException e) {
@@ -139,6 +144,7 @@ public class RoleManagementServiceImpl implements RoleManagementService {
     @Override
     public Response getRole(@PathParam("roleName") String roleName,
                             @HeaderParam("If-Modified-Since") String ifModifiedSince) {
+        RequestValidationUtil.validateRoleName(roleName);
         RoleWrapper roleWrapper = new RoleWrapper();
         try {
             final UserStoreManager userStoreManager = DeviceMgtAPIUtils.getUserStoreManager();
@@ -162,6 +168,10 @@ public class RoleManagementServiceImpl implements RoleManagementService {
                 roleWrapper.setPermissionList(rolePermissions);
                 String[] permListAr = new String[permList.size()];
                 roleWrapper.setPermissions(permList.toArray(permListAr));
+            } else {
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("Role name doesn't exist.")
+                                .build());
             }
         } catch (UserStoreException | UserAdminException e) {
             String msg = "Error occurred while retrieving the user role '" + roleName + "'";
@@ -185,10 +195,8 @@ public class RoleManagementServiceImpl implements RoleManagementService {
     @POST
     @Override
     public Response addRole(RoleWrapper roleWrapper) {
-        if (roleWrapper == null) {
-            log.error("Request body is incorrect or empty");
-            return Response.status(Response.Status.BAD_REQUEST).build();
-        }
+        RequestValidationUtil.validateRoleDetails(roleWrapper);
+        RequestValidationUtil.validateRoleName(roleWrapper.getRoleName());
         try {
             UserStoreManager userStoreManager = DeviceMgtAPIUtils.getUserStoreManager();
             if (log.isDebugEnabled()) {
@@ -218,9 +226,8 @@ public class RoleManagementServiceImpl implements RoleManagementService {
     @Path("/{roleName}")
     @Override
     public Response updateRole(@PathParam("roleName") String roleName, RoleWrapper roleWrapper) {
-        if (roleWrapper == null) {
-            return Response.status(Response.Status.BAD_REQUEST).entity("Request body is incorrect or empty").build();
-        }
+        RequestValidationUtil.validateRoleName(roleName);
+        RequestValidationUtil.validateRoleDetails(roleWrapper);
         String newRoleName = roleWrapper.getRoleName();
         try {
             final UserStoreManager userStoreManager = DeviceMgtAPIUtils.getUserStoreManager();
@@ -265,6 +272,7 @@ public class RoleManagementServiceImpl implements RoleManagementService {
     @Path("/{roleName}")
     @Override
     public Response deleteRole(@PathParam("roleName") String roleName) {
+        RequestValidationUtil.validateRoleName(roleName);
         try {
             final UserStoreManager userStoreManager = DeviceMgtAPIUtils.getUserStoreManager();
             final AuthorizationManager authorizationManager = DeviceMgtAPIUtils.getAuthorizationManager();
@@ -288,9 +296,8 @@ public class RoleManagementServiceImpl implements RoleManagementService {
     @Path("/{roleName}/users")
     @Override
     public Response updateUsersOfRole(@PathParam("roleName") String roleName, List<String> users) {
-        if (users == null || users.size() == 0) {
-            return Response.status(Response.Status.BAD_REQUEST).entity("No users are found in the request").build();
-        }
+        RequestValidationUtil.validateRoleName(roleName);
+        RequestValidationUtil.validateUsers(users);
         try {
             final UserStoreManager userStoreManager = DeviceMgtAPIUtils.getUserStoreManager();
             if (log.isDebugEnabled()) {
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/UserManagementServiceImpl.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/UserManagementServiceImpl.java
index f98938cc20..a7d9794773 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/UserManagementServiceImpl.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/UserManagementServiceImpl.java
@@ -27,11 +27,12 @@ import org.wso2.carbon.device.mgt.common.DeviceManagementException;
 import org.wso2.carbon.device.mgt.core.service.DeviceManagementProviderService;
 import org.wso2.carbon.device.mgt.core.service.EmailMetaInfo;
 import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
-import org.wso2.carbon.device.mgt.jaxrs.beans.OldPasswordResetWrapper;
-import org.wso2.carbon.device.mgt.jaxrs.beans.UserList;
 import org.wso2.carbon.device.mgt.jaxrs.beans.UserWrapper;
 import org.wso2.carbon.device.mgt.jaxrs.service.api.UserManagementService;
-import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.UnexpectedServerErrorException;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.*;
+import org.wso2.carbon.device.mgt.jaxrs.beans.OldPasswordResetWrapper;
+import org.wso2.carbon.device.mgt.jaxrs.beans.UserList;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.NotFoundException;
 import org.wso2.carbon.device.mgt.jaxrs.util.Constants;
 import org.wso2.carbon.device.mgt.jaxrs.util.CredentialManagementResponseBuilder;
 import org.wso2.carbon.device.mgt.jaxrs.util.DeviceMgtAPIUtils;
@@ -42,7 +43,6 @@ import org.wso2.carbon.utils.multitenancy.MultitenantConstants;
 import javax.ws.rs.*;
 import javax.ws.rs.core.MediaType;
 import javax.ws.rs.core.Response;
-import java.io.UnsupportedEncodingException;
 import java.util.*;
 
 @Path("/users")
@@ -65,8 +65,10 @@ public class UserManagementServiceImpl implements UserManagementService {
                             " already exists. Therefore, request made to add user was refused.");
                 }
                 // returning response with bad request state
-                return Response.status(Response.Status.CONFLICT).entity("User by username: " + userWrapper.getUsername() +
-                        " already exists. Therefore, request made to add user was refused.").build();
+                throw new ConflictException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(409l).setMessage("User by username: " +
+                                userWrapper.getUsername() +  " already exists. Therefore, request made to add user " +
+                                "was refused.").build());
             } else {
                 String initialUserPassword = this.generateInitialUserPassword();
                 Map<String, String> defaultUserClaims =
@@ -186,8 +188,9 @@ public class UserManagementServiceImpl implements UserManagementService {
                     log.debug("User by username: " + username + " does not exist.");
                 }
                 // returning response with bad request state
-                return Response.status(Response.Status.NOT_FOUND).entity(
-                        "User by username: " + username + " does not exist").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("User doesn't exist.")
+                                .build());
             }
         } catch (UserStoreException e) {
             String msg = "ErrorResponse occurred while retrieving information of the user '" + username + "'";
@@ -243,9 +246,10 @@ public class UserManagementServiceImpl implements UserManagementService {
                     log.debug("User by username: " + userWrapper.getUsername() +
                             " doesn't exists. Therefore, request made to update user was refused.");
                 }
-                return Response.status(Response.Status.CONFLICT).entity("User by username: " +
-                        userWrapper.getUsername() + " doesn't  exists. Therefore, request made to update user was " +
-                        "refused.").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("User by username: " +
+                                userWrapper.getUsername() + " doesn't  exists. Therefore, request made to update user" +
+                                " was refused.").build());
             }
         } catch (UserStoreException e) {
             String msg = "Exception in trying to update user by username: " + userWrapper.getUsername();
@@ -293,8 +297,9 @@ public class UserManagementServiceImpl implements UserManagementService {
                     log.debug("User by username: " + username + " does not exist for removal.");
                 }
                 // returning response with bad request state
-                return Response.status(Response.Status.NOT_FOUND).entity("User by username: " + username +
-                        " does not exist for removal.").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("User by username: " +
+                                username + " does not exist for removal.").build());
             }
         } catch (UserStoreException e) {
             String msg = "Exception in trying to remove user by username: " + username;
@@ -318,8 +323,9 @@ public class UserManagementServiceImpl implements UserManagementService {
                 if (log.isDebugEnabled()) {
                     log.debug("User by username: " + username + " does not exist for role retrieval.");
                 }
-                return Response.status(Response.Status.NOT_FOUND).entity("User by username: " + username +
-                        " does not exist for role retrieval.").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("User by username: " + username +
+                                " does not exist for role retrieval.").build());
             }
         } catch (UserStoreException e) {
             String msg = "Exception in trying to retrieve roles for user by username: " + username;
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/admin/DeviceManagementAdminServiceImpl.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/admin/DeviceManagementAdminServiceImpl.java
index 46f80d18bf..589127b211 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/admin/DeviceManagementAdminServiceImpl.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/admin/DeviceManagementAdminServiceImpl.java
@@ -28,8 +28,8 @@ import org.wso2.carbon.device.mgt.common.DeviceManagementException;
 import org.wso2.carbon.device.mgt.jaxrs.beans.DeviceList;
 import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
 import org.wso2.carbon.device.mgt.jaxrs.service.api.admin.DeviceManagementAdminService;
-import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.UnauthorizedAccessException;
-import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.UnexpectedServerErrorException;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.*;
+import org.wso2.carbon.device.mgt.jaxrs.service.impl.util.NotFoundException;
 import org.wso2.carbon.device.mgt.jaxrs.util.DeviceMgtAPIUtils;
 
 import javax.ws.rs.*;
@@ -66,8 +66,9 @@ public class DeviceManagementAdminServiceImpl implements DeviceManagementAdminSe
             List<Device> devices = DeviceMgtAPIUtils.getDeviceManagementService().
                 getDevicesByNameAndType(name, type, offset, limit);
             if (devices == null || devices.size() == 0) {
-                return Response.status(Response.Status.NOT_FOUND).entity("No device, which carries the name '" +
-                    name + "', is currently enrolled in the system").build();
+                throw new NotFoundException(
+                        new ErrorResponse.ErrorResponseBuilder().setCode(404l).setMessage("No device, which carries" +
+                                " the name '" + name + "', is currently enrolled in the system").build());
             }
 
             // setting up paginated result
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/util/ConflictException.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/util/ConflictException.java
new file mode 100644
index 0000000000..6afbf6f50a
--- /dev/null
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/util/ConflictException.java
@@ -0,0 +1,34 @@
+/*
+ *   Copyright (c) 2016, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
+ *
+ *   WSO2 Inc. licenses this file to you under the Apache License,
+ *   Version 2.0 (the "License"); you may not use this file except
+ *   in compliance with the License.
+ *   You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *   Unless required by applicable law or agreed to in writing,
+ *   software distributed under the License is distributed on an
+ *   "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *   KIND, either express or implied.  See the License for the
+ *   specific language governing permissions and limitations
+ *   under the License.
+ *
+ */
+package org.wso2.carbon.device.mgt.jaxrs.service.impl.util;
+
+import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
+
+import javax.ws.rs.WebApplicationException;
+import javax.ws.rs.core.Response;
+
+public class ConflictException extends WebApplicationException {
+
+    private static final long serialVersionUID = 14234272342342340L;
+
+    public ConflictException(ErrorResponse error) {
+        super(Response.status(Response.Status.CONFLICT).entity(error).build());
+    }
+
+}
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/util/NotFoundException.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/util/NotFoundException.java
new file mode 100644
index 0000000000..a427e942b9
--- /dev/null
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/util/NotFoundException.java
@@ -0,0 +1,34 @@
+/*
+ *   Copyright (c) 2016, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
+ *
+ *   WSO2 Inc. licenses this file to you under the Apache License,
+ *   Version 2.0 (the "License"); you may not use this file except
+ *   in compliance with the License.
+ *   You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *   Unless required by applicable law or agreed to in writing,
+ *   software distributed under the License is distributed on an
+ *   "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *   KIND, either express or implied.  See the License for the
+ *   specific language governing permissions and limitations
+ *   under the License.
+ *
+ */
+package org.wso2.carbon.device.mgt.jaxrs.service.impl.util;
+
+import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
+
+import javax.ws.rs.WebApplicationException;
+import javax.ws.rs.core.Response;
+
+public class NotFoundException extends WebApplicationException {
+
+    private static final long serialVersionUID = 147943572342342340L;
+
+    public NotFoundException(ErrorResponse error) {
+        super(Response.status(Response.Status.NOT_FOUND).entity(error).build());
+    }
+
+}
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/util/RequestValidationUtil.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/util/RequestValidationUtil.java
index b2dbecb194..f4defbdfad 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/util/RequestValidationUtil.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/util/RequestValidationUtil.java
@@ -18,12 +18,10 @@
  */
 package org.wso2.carbon.device.mgt.jaxrs.service.impl.util;
 
+import org.wso2.carbon.device.mgt.common.DeviceIdentifier;
+import org.wso2.carbon.device.mgt.common.configuration.mgt.PlatformConfiguration;
 import org.wso2.carbon.device.mgt.common.notification.mgt.Notification;
-import org.wso2.carbon.device.mgt.jaxrs.beans.ApplicationWrapper;
-import org.wso2.carbon.device.mgt.jaxrs.beans.ErrorResponse;
-import org.wso2.carbon.device.mgt.jaxrs.beans.OldPasswordResetWrapper;
-
-import javax.ws.rs.core.Response;
+import org.wso2.carbon.device.mgt.jaxrs.beans.*;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -247,6 +245,57 @@ public class RequestValidationUtil {
         }
     }
 
+    public static void validateUpdateConfiguration(PlatformConfiguration config) {
+        if (config == null) {
+            throw new InputValidationException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(400l).setMessage("Configurations are not defined.")
+                            .build());
+        } else if (config.getConfiguration() == null || config.getConfiguration().size() == 0) {
+            throw new InputValidationException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(400l).setMessage("Does not contain any " +
+                            "configuration entries.").build());
+        }
+    }
+
+    public static void validateDeviceIdentifiers(List<DeviceIdentifier> deviceIdentifiers) {
+        if (deviceIdentifiers == null || deviceIdentifiers.size() == 0) {
+            throw new InputValidationException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(400l).setMessage("Device identifier list is " +
+                            "empty.").build());
+        }
+    }
+
+    public static void validatePolicyDetails(PolicyWrapper policyWrapper) {
+        if (policyWrapper == null) {
+            throw new InputValidationException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(400l).setMessage("Policy is empty.").build());
+        }
+    }
+
+    public static void validatePolicyIds(List<Integer> policyIds) {
+        if (policyIds == null || policyIds.size() == 0) {
+            throw new InputValidationException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(400l).setMessage("Policy Id list is empty.").build
+                            ());
+        }
+    }
+
+    public static void validateRoleName(String roleName) {
+        if (roleName == null || roleName.isEmpty()) {
+            throw new InputValidationException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(400l).setMessage("Role name isn't valid.").build
+                            ());
+        }
+    }
+
+    public static void validateUsers(List<String> users) {
+        if (users == null || users.size() == 0) {
+            throw new InputValidationException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(400l).setMessage("User list isn't valid.").build
+                            ());
+        }
+    }
+
     public static void validateCredentials(OldPasswordResetWrapper credentials) {
         if (credentials == null || credentials.getNewPassword() == null || credentials.getOldPassword() == null) {
             throw new InputValidationException(
@@ -255,4 +304,12 @@ public class RequestValidationUtil {
         }
     }
 
+    public static void validateRoleDetails(RoleWrapper roleWrapper) {
+        if (roleWrapper == null) {
+            throw new InputValidationException(
+                    new ErrorResponse.ErrorResponseBuilder().setCode(400l).setMessage("Request body is incorrect or" +
+                            " empty").build());
+        }
+    }
+
 }