diff --git a/src/main/java/org/gcube/portal/threadlocalexec/SmartGearsPortalValve.java b/src/main/java/org/gcube/portal/threadlocalexec/SmartGearsPortalValve.java
index ad5768d..13b9812 100644
--- a/src/main/java/org/gcube/portal/threadlocalexec/SmartGearsPortalValve.java
+++ b/src/main/java/org/gcube/portal/threadlocalexec/SmartGearsPortalValve.java
@@ -88,8 +88,10 @@ public class SmartGearsPortalValve extends ValveBase  {
 				return UserLocalServiceUtil.getUser(userId).getScreenName();
 			} catch (NumberFormatException e) {
 				_log.error("The userId is not a number -> " + userId);
+				return null;
 			} catch (Exception e) {
 				_log.error("The userId does not belong to any user -> " + userId);
+				return null;
 			}
 		} 
 		return null;