diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/resources/utils/HeaderUtility.java b/src/main/java/org/gcube/informationsystem/resourceregistry/resources/utils/HeaderUtility.java
index cc457c3..bbbfc5e 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/resources/utils/HeaderUtility.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/resources/utils/HeaderUtility.java
@@ -41,12 +41,14 @@ public class HeaderUtility {
 		String creator = org.gcube.informationsystem.model.embedded.Header.UNKNOWN_USER;
 		try {
 			Caller caller = AuthorizationProvider.instance.get();
-			ClientInfo clientInfo = caller.getClient();
-			String clientId = clientInfo.getId();
-			if (clientId != null && clientId.compareTo("") != 0) {
-				creator = clientId;
-			} else {
-				throw new Exception("Username null or empty");
+			if(caller!=null){
+				ClientInfo clientInfo = caller.getClient();
+				String clientId = clientInfo.getId();
+				if (clientId != null && clientId.compareTo("") != 0) {
+					creator = clientId;
+				} else {
+					throw new Exception("Username null or empty");
+				}
 			}
 		} catch (Exception e) {
 			logger.error("Unable to retrieve user");