What OS? What version of Firefox?

Hey Vernon,

Yes, it does happen, but here's the workaround for this unfortunate common issue. In your sessionstore-backups folder just look for any file with a date before the issue and the one with the bigger size. https://support.mozilla.org/en-US/questions/1477659#answer-1693216

That should work. A couple scenarios where it might not:

(1) Firefox isn't saving browsing history -- saving history is necessary to save open tabs

(2) Firefox thinks the main window was closed before you quit Firefox

To restore a closed window, go to the History menu and use the Recently Closed Windows list (or try Ctrl+Shift+N).

(3) Firefox never quit -- this could happen if a Firefox window is open a different desktop or there's a hidden process

I am not sure if this helps in the troubleshooting, but I have this problem too. Background: I am using MacOS. I have implemented recommendations from support sites to restore session. When my session doesn't restore, it is because I have to perform a MacOS update. In order to continue with the update, MacOS forces me to close Firefox in order to install updates.

I still have the problem of my session not being restored even when I go to Settings | History | Recently closed tabs | Reopen all tabs

Hi Nikita, do you mean MacOS closed Firefox for you, or you went to one of these:

• menu > Quit
• (menu bar) Firefox > Quit

(I'm a Windows person, so I'm guessing where Quit is on your menus.)

After your next Firefox startup, you may need to use either or both of these:

• History > Restore previous session [missing if session was restored automatically or session history files are not available]
• History > Recently closed windows [Firefox should remember up to 3 closed windows]