I hit this sync failure on the trunk nightly today. The error dialog on the UI appeared with an unhelpful note saying "Unknown error". Force resyncing fixed it and the sync was successful. Dupme if known. Log file attached Repro: 1) install mac nightly trunk: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0b10pre) Gecko/20110112 Firefox/4.0b10pre 2) let the auto sync detection kick in on the timer 3) Verify a notification error appears with Unknown Error, and sync log mentions history failed to sync Expected: - no history fail

mrz has been hitting this bug with history (sadly I believe there's no bug on file for his issue) and ehsan with bookmarks (bug 623605). They may or may not be due to the same underlying problem, so I'm not duping them just yet.

I'm pretty confident we've identified bug 617650 as the root issue of this bug.

I'm still seeing this error in today's Minefield trunk nightly, from http://hg.mozilla.org/mozilla-central/rev/6a097e294828 (This includes the patch for bug 617650.) Nominating for blocking2.0. This error occurs on every sync with my account, and the error UI reappears every few minutes if I close it.

(In reply to comment #4) > I'm still seeing this error in today's Minefield trunk nightly, from > http://hg.mozilla.org/mozilla-central/rev/6a097e294828 > > (This includes the patch for bug 617650.) > > Nominating for blocking2.0. This error occurs on every sync with my account, > and the error UI reappears every few minutes if I close it. Matt: the fix doesn't handle the bad record; it prevents it being created (we hope). You'll continue to get the error until either: * The record is deleted from the server (e.g., by Reset Sync > "Replace all on server" on a machine with all the data you want to keep) * Bug 622762 (IIRC) is finished.

Thanks, Richard. Cancelling blocking2.0:? on this bug because bug 622762 is already blocking.

This should be fixed now (bug 617650 prevents this from happening, bug 622762 no longer prevents Sync from finishing.)

verified with nightly minefield builds of 20110218