The persistent cc-800 error that is a subject of discussion in other threads here may be triggered by a restore. For a year or more, I've had periods where these errors were returned for Amazon Store Card on every sync. Then they go away for a long period. Then they return. The errors are spurious. Transactions are correctly and promptly updated despite the error. And for me, the errors only occur on Amazon Store Card. After a period of not getting the errors, they started again immediately after I restored from a backup. That's one occurrence. So it could be a coincidence.