Not Listing Errors

Global errors like this typically indicate something is failing in the XML parser, although I have never seen a blank error code before. Can you supply more details on the data you are trying to sync?

Update to this: we have encountered this in the wild and it was caused by invalid characters sneaking their way into the batch XML, normally via user input fields like last name. Unfortunately, unless you can visually discern from the records which account is causing the problem you may need to add items from this batch back to the retry queue in small batches until you find the one causing the error.