diff --git a/src/main/java/org/gcube/portlets/user/workspace/server/GWTWorkspaceServiceImpl.java b/src/main/java/org/gcube/portlets/user/workspace/server/GWTWorkspaceServiceImpl.java
index a1aa1c4..b751c4c 100644
--- a/src/main/java/org/gcube/portlets/user/workspace/server/GWTWorkspaceServiceImpl.java
+++ b/src/main/java/org/gcube/portlets/user/workspace/server/GWTWorkspaceServiceImpl.java
@@ -2870,12 +2870,14 @@ public class GWTWorkspaceServiceImpl extends RemoteServiceServlet implements GWT
 
 				//TO REMOVE ADMINS
 				List<String> admins = mapACL.get(ACLType.ADMINISTRATOR);
-				for (String admin : admins) {
-					boolean removed = listLogins.remove(admin);
-					workspaceLogger.info("Reject username: "+admin +" as "+ACLType.ADMINISTRATOR);
-					if(removed){
-						String fullname = isTestMode()?admin: UserUtil.getUserFullName(admin);
-						errors.add("Unable to grant the privilege "+settingACL+" for "+fullname+", he/she is an: "+ ACLType.ADMINISTRATOR);
+				if(admins !=null){
+					for (String admin : admins) {
+						boolean removed = listLogins.remove(admin);
+						workspaceLogger.info("Reject username: "+admin +" as "+ACLType.ADMINISTRATOR);
+						if(removed){
+							String fullname = isTestMode()?admin: UserUtil.getUserFullName(admin);
+							errors.add("Unable to grant the privilege "+settingACL+" for "+fullname+", he/she is an: "+ ACLType.ADMINISTRATOR);
+						}
 					}
 				}