Open previous windows and tabs: why does this occasionally fail?

[SimonSYI]

Opened Firefox this morning, no previous tabs were opened, just the Home. This happened previously, probably once every 2-3 weeks. It's extremely frustrating, I lost about fifteen relevant tabs that were open.

Firefox was closed normally so why does this happen at intervals and is there anything that can be done to avoid it?

[jscher2000]

Sorry to hear about this problem. Two things to check:

(1) History > Recent Closed Windows

If Firefox closed your main window before it closed a different or possibly hidden window, then the main window won't be re-opened automatically. Check the History menu, either:

• main menu button > History > Recent Closed Windows
• (menu bar) History > Recent Closed Windows

to see whether you can still restore the window. To avoid this kind of sequence problem, close out Firefox using the menu. On Windows, that's "Exit" and on Mac and Linux, it's "Quit."

(2) Cleaners

Some users have privacy or utility software that clean up browser data. If all of your tabs disappear and there are no recently closed windows, it's possible that one of these programs (such as Ccleaner or Advanced System Care) removed the data.

[SimonSYI]

Thanks for the reply, but History > Recently closed windows was the first thing I checked and it was clear. I do always close Firefox correctly, it hadn't crashed or had an atyical exit.

I haven't used Ccleaner or anything like that for years.

[jscher2000]

When this happens, do you lose all the files in the sessionstore-backups folder? That folder is in your profile. See: https://support.mozilla.org/kb/profiles-where-firefox-stores-user-data

If you have files in there from before the data loss, I have a tool to extract out the URLs that you could consider using: https://www.jeffersonscher.com/ffu/scrounger.html