We'll say so here when the server is truly working.

Please stop theorizing about what works and what doesn't. Save uploads are broken, please don't try to upload saves until we've confirmed that the issue has been resolved.

The server is fixed again now.

Saves uploaded on Jan 4th during the 11-hour period between 6:00 AM UTC and 5:00 PM UTC may have been lost. When the server runs out of space, there is no extra copy of saves you uploaded, so if you didn't preserve a local copy, we don't have one either.

I unpublished all affected saves on By Date. If your save was affected, it will have a broken thumbnail, but you can try doing history:XXXXXXX with your save ID to see if there's any working older versions.

Some saves during this range uploaded fine. The first and last hour of that range has a lot of successful saves. In between, saves would upload only if someone else deleted another save, making a little bit of room. So that's why some saves made it through fine.

Edit: Fixed the timestamps, originally I said 1am to noon, but that was in my time zone (EST), not UTC.

Try the history:XXXXXXX trick @jacob1 mentioned above.