Yes, it does happen. Have a look at the below links. https://support.mozilla.org/en-US/questions/1449521 https://support.mozilla.org/en-US/questions/1420979#answer-1602679 https://support.mozilla.org/en-US/questions/1440459#answer-1637875

Thanks for picking this up Jonzn4SUSE.

I followed your instructions relating to the sessionstore-backups folder and your scrounger (many thanks for creating that!). Unfortunately nothingg pre-wipeout.

On thing is that you mention a Library toolbar button: I don't seem to have this in my Firefox. Please could you let me know where I can find it, or send a screen shot?

I've looked through the 3 links to previous help you've offered and nothing seems to be relevant for me since there aren't any .jsonlz4 or similar files with any tab information prior to this issue.

One of the threads mentions different profiles. I'm logged into FF using my main personal email address, so I assume that's the situation before this issue, but I can't remember. If I have another profile somewhere or if I wasn't logged into FF at all prior to the issue, how would I find out and what would I do?

Post a similar screenshot of your sessionstore-backup folder. If there is nothing dated before your issue, then it's game over. I've had that issue in the past which is why about 1 time a week or so, I make a copy of the sessionstore-backup folder. see screenshot A few months ago I noticed in Nightly that it erased everything in my sessionstore-backup folder. Looking at my copy folder, I can go back if needed by renaming one of the files to my session file. see screenshot