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 aaa45cdf61..a2e1ddde6c 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
@@ -117,7 +117,7 @@ public interface DeviceManagementService {
                     name = "If-Modified-Since",
                     value = "Timestamp of the last modified date",
                     required = false)
-            @HeaderParam("If-Modified-Since") Date timestamp,
+            @HeaderParam("If-Modified-Since") String timestamp,
             @ApiParam(
                     name = "offset",
                     value = "Starting point within the complete list of items qualified.",
@@ -191,7 +191,7 @@ public interface DeviceManagementService {
                     name = "If-Modified-Since",
                     value = "Timestamp of the last modified date",
                     required = false)
-            @HeaderParam("If-Modified-Since") Date timestamp);
+            @HeaderParam("If-Modified-Since") String timestamp);
 
 
     @GET
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 64fc9bd47e..34e36ed2e7 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
@@ -323,7 +323,7 @@ public interface UserManagementService {
                     name = "If-Modified-Since",
                     value = "Timestamp of the last modified date",
                     required = false)
-            @HeaderParam("If-Modified-Since") Date timestamp,
+            @HeaderParam("If-Modified-Since") String timestamp,
             @ApiParam(
                     name = "offset",
                     value = "Starting point within the complete list of items qualified.",
@@ -389,7 +389,7 @@ public interface UserManagementService {
                     name = "If-Modified-Since",
                     value = "Timestamp of the last modified date",
                     required = false)
-            @HeaderParam("If-Modified-Since") Date timestamp,
+            @HeaderParam("If-Modified-Since") String timestamp,
             @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/admin/GroupManagementAdminService.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/admin/GroupManagementAdminService.java
index 7e63ae239f..ac26479b47 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/admin/GroupManagementAdminService.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/api/admin/GroupManagementAdminService.java
@@ -82,7 +82,7 @@ public interface GroupManagementAdminService {
                     name = "If-Modified-Since",
                     value = "Timestamp of the last modified date",
                     required = false)
-            @HeaderParam("If-Modified-Since") Date timestamp,
+            @HeaderParam("If-Modified-Since") String timestamp,
             @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/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 b36903c9c7..b5c95c099a 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
@@ -62,7 +62,7 @@ public class DeviceManagementServiceImpl implements DeviceManagementService{
             @QueryParam("roleName") String roleName,
             @QueryParam("ownership") String ownership,
             @QueryParam("status") String status,
-            @HeaderParam("If-Modified-Since") Date timestamp,
+            @HeaderParam("If-Modified-Since") String timestamp,
             @QueryParam("offset") int offset,
             @QueryParam("limit") int limit) {
         try {
@@ -86,7 +86,7 @@ public class DeviceManagementServiceImpl implements DeviceManagementService{
     @Override
     public Response getDevicesInfo(
             List<DeviceIdentifier> deviceIds,
-            @HeaderParam("If-Modified-Since") Date timestamp) {
+            @HeaderParam("If-Modified-Since") String timestamp) {
         DeviceInformationManager informationManager;
         List<DeviceInfo> deviceInfo;
         try {
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 9807f7fd7b..0ab4ab55ff 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
@@ -323,7 +323,7 @@ public class UserManagementServiceImpl implements UserManagementService {
 
     @GET
     @Override
-    public Response getUsers(@QueryParam("filter") String filter, @HeaderParam("If-Modified-Since") Date timestamp,
+    public Response getUsers(@QueryParam("filter") String filter, @HeaderParam("If-Modified-Since") String timestamp,
                              @QueryParam("offset") int offset,
                              @QueryParam("limit") int limit) {
         if (log.isDebugEnabled()) {
@@ -357,7 +357,7 @@ public class UserManagementServiceImpl implements UserManagementService {
     @GET
     @Path("/usernames")
     @Override
-    public Response getUserNames(@QueryParam("filter") String filter, @HeaderParam("If-Modified-Since") Date timestamp,
+    public Response getUserNames(@QueryParam("filter") String filter, @HeaderParam("If-Modified-Since") String timestamp,
                                  @QueryParam("offset") int offset, @QueryParam("limit") int limit) {
         if (log.isDebugEnabled()) {
             log.debug("Getting the list of users with all user-related information using the filter : " + filter);
diff --git a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/admin/GroupManagementAdminServiceImpl.java b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/admin/GroupManagementAdminServiceImpl.java
index 88c1561c6b..aaf8307131 100644
--- a/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/admin/GroupManagementAdminServiceImpl.java
+++ b/components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/admin/GroupManagementAdminServiceImpl.java
@@ -41,7 +41,7 @@ public class GroupManagementAdminServiceImpl implements GroupManagementAdminServ
     @Override
     public Response getGroupsOfUser(
             @QueryParam("username") String username,
-            @HeaderParam("If-Modified-Since") Date timestamp,
+            @HeaderParam("If-Modified-Since") String timestamp,
             @QueryParam("offset") int offset,
             @QueryParam("limit") int limit) {
         try {