tabs reverted to earlier version

Don't close Firefox. (Shutdown overwrites any previous session store data.)

Go to about:profiles or about:support (or menu Help › More troubleshoot info) and click the button to open your profile folder. Make a copy/backup of any and all files and folders named sessionstore.* or sessionstore–* so that you can go back to them if need be.

Now if you look at the time stamps and file sizes of the older versions in sessionstore–backups folder you might be able to tell if a version in there might contain the data you're looking for. (If so, again, make a copy of the whole folder and the individual file versions, ideally create a backup by zipping them to a safe location — so that you can then use the individual versions to either launch in a new profile, or swap into the existing one, to try restarting the browser with that particular session store…)

jbr, this is very helpful, i did copy the whole profile in a different place, but too late - the files in sessionstore-backups are stamped with a time after the wrong tabs opened. i didn't close the browser but rebooted, likely this, too, overwrote the previous tabs? my question is, if the previous set of tabs was available to reload, might not a more recent set of tabs (but before the problem) also be available, somewhere? more importantly, for the future: how do i start firefox with a previously saved session? thank you!

thank you! would you be able to help, please, with merging current with previous bookmarks? - or just recovering the 'toolbar' and 'other' bookmarks? (the other thread i opened). no worries if not, i'll do it manually, somehow, but it'd be good if you had a quick and safe fix. thank you!

I can look into the other question for sure — it just seems weird that "for unrelated reasons" two disjunct systems would lose data/days actually similarly to as if they've been rolled back in time — that sounds more like a system utility performed some data restore, like from a backup point. (Or, a fault in caching failed to write data to disk and only kept the changes in memory.)

I'll check the other thread in more detail in a bit.

I don't think the problems happened at the same time. First the tabs reverted to the version from a few days ago, but the bookmarks loaded normally. But I wasn't sure they were the last version, so I choose to restore the more recent bookmarks backup from Manage bookmarks. This, from some reason, made all bookmarks disappear. I rebooted and retried a number of times, and the best I got was that the bookmarks were loaded - one I know I had saved recently was there, so presumably this was the most recent version - but the Bookmarks toolbar and Other bookmarks were empty. No idea why this happened. Thank you. I found this: https://github.com/SVO20/jsonlz4_to_html but haven't managed to make it work yet. Then I could probably import the .html file and remove the duplicates.