diff --git a/src/main/java/org/gcube/portal/threadlocalexec/SmartGearsPortalValve.java b/src/main/java/org/gcube/portal/threadlocalexec/SmartGearsPortalValve.java
index 79e84a0..300f7cc 100644
--- a/src/main/java/org/gcube/portal/threadlocalexec/SmartGearsPortalValve.java
+++ b/src/main/java/org/gcube/portal/threadlocalexec/SmartGearsPortalValve.java
@@ -81,7 +81,7 @@ public class SmartGearsPortalValve extends ValveBase  {
 	 */
 	public static String getCurrentUsername(HttpServletRequest httpServletRequest) {
 		String userIdNo = httpServletRequest.getHeader(PortalContext.USER_ID_ATTR_NAME);
-		if (userIdNo != null) {
+		if (userIdNo != null && userIdNo.compareTo("undefined") != 0) {
 			long userId = -1;
 			try {
 				userId = Long.parseLong(userIdNo);