HTTP Result Code: 500 Debugging information follows.

Hi all;

while updating from nodewords to metadata this error occured

An AJAX HTTP error occurred. HTTP Result Code: 500 Debugging information follows. Path: /batch?id=12543&op=do StatusText: Service unavailable (with message) ResponseText: EntityMalformedException: Missing bundle property on entity of type node. in entity_extract_ids() (line 7663 of /home/content/61/10191161/html/includes/com

please help solving this error, what is it and how can it be solved
your quick reply is highly appreciated