You may have corrupt sessionstore [v56] sessionstore.jsonlz4 file(s). Delete all sessionstore* files and the sessionstore-backups folder.

Type about:support<enter> in the address bar.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder

Linux: Under the page logo on the left side, you will see Application Basics. Under this find Profile Directory. To its right press the button Open Directory.

Locate the above file. Then rename or delete it. Restart Firefox.

Don't delete the files if you need to rescue any data from them, just move them out of the profile folder to some location where Firefox doesn't look for them. You can try to read out their contents using this tool: https://www.jeffersonscher.com/res/scrounger.html

Still not ok. I had there 2 files. I delete it and still not working.

One more thing. I have notice that when I close Firefox this folder sassionstore -backups is delete.

Hi Niemen, another user reported a similar unexplained loss of the sessionstore-backups folder. I'll link to that thread in case it gives you any ideas:

https://support.mozilla.org/questions/1274827

(The other poster's method of doing an uninstall, disk cleanup, and reinstall sounds a bit drastic, so hopefully something else will work.)

So....I uninstall firefox, I cleanup disk.....at thought that it works.....till when I connect with my Firefox account. All cards has been imported but memory about cards is lost. I have no idea what I did wrong. Dou you know what can be wrong? Is there any setup in Firefox account that in each browser it will clean or......

Niemen said

All cards has been imported but memory about cards is lost.

I don't know what you mean -- the tabs loaded but the tabs are blank??

Sorry for my english :) So... all bookmarks has been imported but not tabs. I also noticed something strange. When I will leave a browser opened and make restart of system, then after restart all tabs are oki, even when I'm connected with my Account. Same for expample when I tried change language of Browser for anglish an hit apply and resrt button, in Options, but when I close browser using "X", all is cleaned.

Try this instead; Windows: Menu > File => Exit Mac: Menu > Firefox => Quit Firefox Linux: Menu > File => Quit

Is it this what you think of? If yes, still same issue.

so, right now I lost all tabs on second hardware, and issue with saving tabs is same right now. I lost a lot of tabs what was very important for me.

If you need to rescue any data from the sessionstore files, just move them out of the profile folder to some location where Firefox doesn't look for them. You can try to read out their contents using this tool: https://www.jeffersonscher.com/res/scrounger.html

So if I understand the current status:

• Connecting to your Firefox Account (Sync) did not bring back the earlier tabs -- I can't help with this issue

• When Firefox crashes (or is killed in Task Manager): tabs are restored -- this is working as expected

• When Firefox exits normally:
  • Tabs are not restored
  • The sessionstore-backup folder is completely removed -- Firefox doesn't do this, and add-ons should not be able to do this

Is there any "clean up" or "privacy" software on your computer that might detect a normal Firefox exit and remove session history files? Some programs that may clean up browser data include CCleaner and Advanced SystemCare.

Sprawdź, co masz ustawione w Opcje - Prywatność i bezpieczeństwo -> Historia.

@jscher2000 - yes that is correct. I don't have any cleanup software installed on PC.

@TyDraniu - co masz na myśli jeśli chodzi o te ustawienia, w załączniku moje ustawienia, co do historii.

Masz zaznaczone Czyszczenie historii podczas zamykania przeglądarki Firefox. Ta opcja jest wymieniona w artykule Restore previous session - Configure when Firefox shows your most recent tabs and windows jako powodująca problemy z sesją. Kliknij przycisk Ustawienia… i sprawdź, czy usuwasz Historię na wyjściu z programu.

@TyDraniu - dzieki za pomoc rozwiazalo to problem z tego co widze. BtW niezly nick :) So issue is related to the option about history clearing during closing browser.