I've worked on the same profile for many months. I'm a tab hoarder and as such I've accumulated a lot of them over time. Until today I've always managed to restore sessions, but today Firefox seemingly broke. I closed it, as it was starting to lag and take too many resources. When I restarted, it read my previous session, but didn't load it properly. All tabs list 'New Tab' in window 1, they other window didn't open more than one tab. I tried to restore it through sessions backups, but it didn't help. So I started going back to older session backups, up to 2 months ago, but the same problem persisted. I exported the essentials of my profile, deleted the current one, restored it in a new profile, same problem. I restarted my PC, reinstalled firefox, didn't work. I installed an older version, problem still there. I tried closing all non-essential tabs, including the recent ones that could cause this. I ended up removing 1/3 of the tabs, but still it didn't do anything. Ultimately, I feel like I've tried everything I could think of, but nothing works. For every older session backup, it opens empty tabs. Hopefully someone can help :) Thanks in advance!