diff --git a/src/main/java/org/gcube/data/access/storagehub/AuthorizationChecker.java b/src/main/java/org/gcube/data/access/storagehub/AuthorizationChecker.java
index 016be27..392ccfd 100644
--- a/src/main/java/org/gcube/data/access/storagehub/AuthorizationChecker.java
+++ b/src/main/java/org/gcube/data/access/storagehub/AuthorizationChecker.java
@@ -27,9 +27,9 @@ import org.slf4j.LoggerFactory;
 
 @Singleton
 public class AuthorizationChecker {
-	
+
 	private static Logger log = LoggerFactory.getLogger(AuthorizationChecker.class);
-	
+
 	@Inject
 	Node2ItemConverter node2Item;
 
@@ -42,13 +42,13 @@ public class AuthorizationChecker {
 
 		if (item==null) throw new UserNotAuthorizedException("Insufficent Privileges for user "+login+" to read node with id "+id+": it's  not a valid StorageHub node");
 
-		
-		
+
+
 		if (item.isShared()) {
 			SharedFolder parentShared = node2Item.getItem(retrieveSharedFolderParent(node, session), Excludes.EXCLUDE_ACCOUNTING);
-			
+
 			if (parentShared.getUsers().getMap().keySet().contains(login)) return;
-			
+
 			//CHECKING ACL FOR VREFOLDER AND SHARED FOLDER
 			JackrabbitAccessControlList accessControlList = AccessControlUtils.getAccessControlList(session, parentShared.getPath());
 			AccessControlEntry[] entries = accessControlList.getAccessControlEntries();
@@ -56,9 +56,18 @@ public class AuthorizationChecker {
 			for (AccessControlEntry entry: entries) {
 				log.debug("checking access right for {} with compared with {}",login, entry.getPrincipal());
 				Authorizable authorizable = ((JackrabbitSession) session).getUserManager().getAuthorizable(entry.getPrincipal());
-				//TODO; check why sometimes the next line gets a nullpointer
-				if (!authorizable.isGroup() && entry.getPrincipal().getName().equals(login)) return;
-				if (authorizable.isGroup() && ((Group) authorizable).isMember(userAuthorizable)) return;
+				
+				if (authorizable==null) {
+					log.warn("{} doesn't have a correspondant auhtorizable object, check it ", entry.getPrincipal());
+					continue;
+				}
+				
+				try {
+					if (!authorizable.isGroup() && entry.getPrincipal().getName().equals(login)) return;
+					if (authorizable.isGroup() && ((Group) authorizable).isMember(userAuthorizable)) return;
+				}catch (Throwable e) {
+					log.warn("someting went wrong checking authorizations",e);
+				}
 			}
 			throw new UserNotAuthorizedException("Insufficent Privileges for user "+login+" to read node with id "+id);