Fixed an issue where the blank string is stored instead of NULL in the server table of SQLite database. Fixes #6915

web/pgadmin/browser/server_groups/servers/__init__.py

@@ -811,6 +811,9 @@ class ServerNode(PGChildNodeView):
     @staticmethod
     def _update_server_details(server, sharedserver,
                                config_param_map, arg, value):
+        if value == '':
+            value = None
+
         if server.shared and server.user_id != current_user.id:
             setattr(sharedserver, config_param_map[arg], value)
         else: