So: I toggled 'restore my previous session on startup: and it had been working, but i recall an old bug where sometimes exiting would choose to 'close' the windows behind it, but at least that old bug i could clear with the 'recently closed windows' feature... Today I was prompted to reboot to install updates on my software, and lo an behold, my previous session is gone. Again. And it isn't available in the previously closed tabs. *struggles to avoid swearing* So: I google the matter and find this: https://support.mozilla.org/en-US/questions/1204253 Cool: wait... my previous.js currently CONTAINS my previous session, but firefox said I didn't HAVE a previous session on startup. What is going on here? I'm assuming it could be a bug from the windows update, firefox updating or everything updating at the same time. Probably. So how to make use of the data? i have like 60 tabs here: i don't want to reopen them manually one at a time: oooh this one suggests you can do it manually! https://support.mozilla.org/en-US/questions/1144320 But is the above folder the right place for the renamed file? or somewhere else in firefox memory? Best to ask properly: and suggest that Firefox Sticky a thread for containing the useful 'how to fix when things actually break instead of saying 'just turn it on and it will be good' because this is not the first time firefox has pulled this stunt on me: Bad Canine companion. Stop being Naughty, more web browsing less burning of data please. Anyway: Could anyone give advice on how to persuade firefox to actually look at previous,js when it seems to ignore it on boot sometimes?