Hi

No, unfortunately that is not possible. Firefox Sync is designed to be able to move bookmarks and other data between two or more copies of Firefox - it is not designed as an online backup.

Back up and restore information in Firefox profiles.{web link} I use an add-on that makes backups of my user profile, Just In Case. Unfortunately, it is not compatible with the current Firefox.

Every now and then, open the profile folder and create a copy of the current profile as is to another location on your hard drive. This way you will have a backup.

If you do this each day, you will not lose much data. This should be done with Firefox Closed.

Note: In case you need to restore from these backups, you may need to overwrite old or corrupted files.

WillW said

... Is there any way to "rewind" my Firefox state to a time shortly before I cleared my history?

Sorry that is not possible. Sync stores one data set, so once any deletion is made that is reflected in the data which is stored on the Sync server for your account. As stated by Seburo, there are no "backups" saved on the Sync server, thus no way to "go back" to what was present before the data was deleted.