I just had this problem. Turns out, Firefox saved all my tabs as a closed window. When trying to auto-restore them, it could find no active session — i.e., the list on about:sessionrestore page was empty, and restarting in Safe mode didn’t help.
What to do:
- If your session won’t restore, DON’T close or restart your browser before going to your profile folder and backupping sessionstore.bak (and sessionstore.js if it’s not empty already).
- Open sessionrestore in Notepad.
- It should begin like this:
- If it doesn’t, delete everything in between.
- Save. Make sure the edited file is in your profile folder in place of your empty sessionstore.js. I also put it in place of the old sessionstore.bak. (You should keep the backup of the original files in a different folder in case anything goes wrong.)
- Restart. If it worked, congratulations! If not, you probably had a different problem.
Note: this problem should be very rare. I basically brought it on myself: aborted the program through Task Manager because it couldn’t close for ten minutes and was eating all the memory, so it didn’t finish writing the session file properly. You won’t need to edit it in normal circumstances.