diff --git a/src/main/java/org/gcube/portal/social/networking/ws/methods/v2/Notifications.java b/src/main/java/org/gcube/portal/social/networking/ws/methods/v2/Notifications.java
index d81ebd2..5e192b8 100644
--- a/src/main/java/org/gcube/portal/social/networking/ws/methods/v2/Notifications.java
+++ b/src/main/java/org/gcube/portal/social/networking/ws/methods/v2/Notifications.java
@@ -185,7 +185,7 @@ public class Notifications {
 
 		return Response.status(status).entity(responseBean).build();
 	}
-	
+
 	/**
 	 * Send a Catalogue notification to a given user
 	 * @param event
@@ -225,8 +225,9 @@ public class Notifications {
 			if (! event.idsAsGroup()) {
 				for (int i = 0; i < idsToNotify.length; i++) {
 					String userIdToNotify = idsToNotify[i];
+					String username2Notify = null;
 					try {
-						um.getUserByUsername(userIdToNotify);		
+						username2Notify = um.getUserByUsername(userIdToNotify).getUsername();		
 					}
 					catch (Exception e) {
 						status = Status.NOT_ACCEPTABLE;
@@ -235,13 +236,20 @@ public class Notifications {
 						responseBean.setMessage("Username not found " + userIdToNotify);
 						return Response.status(status).entity(responseBean).build();
 					}
-					deliveryResult 	= 
-							nm.notifyCatalogueEvent(
-									CatalogueEventTypeMapper.getType(event.getType()), 
-									userIdToNotify, 
-									event.getItemId(), 
-									event.getNotifyText(), 
-									event.getItemURL());
+					if (username2Notify != null) {
+						deliveryResult 	= 
+								nm.notifyCatalogueEvent(
+										CatalogueEventTypeMapper.getType(event.getType()), 
+										username, 
+										event.getItemId(), 
+										event.getNotifyText(), 
+										event.getItemURL());
+					} else {
+						status = Status.NOT_ACCEPTABLE;
+						responseBean.setSuccess(false);
+						responseBean.setMessage("Username not found " + userIdToNotify);
+						return Response.status(status).entity(responseBean).build();
+					}
 				}
 			} else { //the ids are contexts
 				for (int i = 0; i < idsToNotify.length; i++) {
@@ -335,8 +343,9 @@ public class Notifications {
 			if (! event.idsAsGroup()) {
 				for (int i = 0; i < idsToNotify.length; i++) {
 					String userIdToNotify = idsToNotify[i];
+					String username2Notify = "";
 					try {
-						um.getUserByUsername(userIdToNotify);		
+						username2Notify = um.getUserByUsername(userIdToNotify).getUsername();		
 					}
 					catch (Exception e) {
 						status = Status.NOT_ACCEPTABLE;
@@ -345,7 +354,7 @@ public class Notifications {
 						responseBean.setMessage("Username not found " + userIdToNotify);
 						return Response.status(status).entity(responseBean).build();
 					}
-					deliveryResult 	= notifyWorkspaceEvent(event, nm, userIdToNotify);
+					deliveryResult 	= notifyWorkspaceEvent(event, nm, username2Notify);
 				}
 			} else { //the ids are contexts
 				for (int i = 0; i < idsToNotify.length; i++) {