Join the AMA (Ask Me Anything) with the Firefox leadership team to celebrate Firefox 20th anniversary and discuss Firefox’s future on Mozilla Connect. Mark your calendar on Thursday, November 14, 18:00 - 20:00 UTC!

This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Why can't I find session store files?

  • 3 cavab
  • 3 have this problem
  • 5 views
  • Last reply by cor-el

more options

I lost all my tabs. Restore previous session is greyed out. I can't find any session store files. This happened after an automatic Windows update overnight (9/14) and a firefox update when I clicked on Firefox this morning.

I lost all my tabs. Restore previous session is greyed out. I can't find any session store files. This happened after an automatic Windows update overnight (9/14) and a firefox update when I clicked on Firefox this morning.

All Replies (3)

more options

You can check the sessionstore-backups folder in the profile folder for a recent upgrade.jsonlz4s file. You can use this tool to check if the file contains that lost sesion.


Firefox uses the sessionstore.jsonlz4 file in the profile folder to store session data. The sessionstore.jsonlz4 file is only present when Firefox is closed. The sessionstore.jsonlz4 file is created from recovery.jsonlz4 when you close Firefox and is removed and copied to previous.jsonlz4 when you start Firefox to make is possible to restore the session at any time.

Backup the session files in the sessionstore-backups folder in the Firefox Profile Folder to make sure not to lose possible important session data. Do NOT close Firefox when Firefox is already running.

You will normally find these files in the sessionstore-backups folder:

  • previous.jsonlz4 (cleanBackup: copy of sessionstore.jsonlz4 from previous session that was loaded successfully)
  • recovery.jsonlz4 (latest version of sessionstore.jsonlz4 written during runtime)
  • recovery.baklz4 (previous version of sessionstore.jsonlz4 written during runtime)
  • upgrade.jsonlz4-<build_id> (backup created during an upgrade of Firefox)

You can copy a file from the sessionstore-backups folder to the main profile and rename the file to sessionstore.jsonlz4 to replace the current file (make sure to backup the current sessionstore.jsonlz4).

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

more options

I used the scrounger tool but only found tabs visited today. I assume that's because I shut down and restarted Firefox yesterday when I was trying different things to restore tabs? Does that mean they're gone forever?

Thanks for the link to scrounger tool. I'll use that if this happens again.

more options

Did you look at the upgrade.jsonlz4 files that Firefox creates when it updates?