Okay - I have some data from the about:sync-log.

Several rows with things like: "1304887316234 Engine.Bookmarks WARN Error decrypting record: Record SHA256 HMAC mismatch: should be 53a0892f07a8139263869a520ed2af79e9abf00cbb3b44978dc34ee094c69ffd, is a5ca86a0f5b48b493ab5ee07b68ee3ad31697b927c92b53281039017c2e31659 No traceback available"

also: 1304887316856 Collection WARN Got exception calling onProgress handler during fetch of https://phx-sync120.services.mozilla.com/1.0/andrewducker/storage/forms?full=1&ids=!!NjPLkpTa,!(*I6ex)wE,... (several pages of gibberish elided)

and numerous other lines of error.

If anyone wants to look into this, I'm happy to provide log file info for them to look into...

Andy

That has happened to many Sync users a lot lately. If it lasted more than 24 hours, I usually just delete my account and set up another one, after that, it will sync normally, until it gives the error again. It's an on-going problem with Sync.

As a warning, if you do so, all of your Sync backups will be gone. And I suggest you backup your bookmarks and passwords before you proceed, just in case. Also be sure to write down all of your log-in information, especially the Sync key.

Or you can keep on waiting, it might be back to normal again, but no telling when.