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Firefox 54.0.1 lost 400 tabs

I have a lot of tabs I admit. Firefox always restores the 500+ tabs I use but one day I realized that about 400 tabs are lost. Then I upgraded to ff56, then ff57 no luck. After upgrading to ff57 my add-ons are also disabled.

I need something that could find the last session (apparently session restore files are not stored under installation folder in ff57) so that I could manually enter the pages. Or any ideas?

I have a lot of tabs I admit. Firefox always restores the 500+ tabs I use but one day I realized that about 400 tabs are lost. Then I upgraded to ff56, then ff57 no luck. After upgrading to ff57 my add-ons are also disabled. I need something that could find the last session (apparently session restore files are not stored under installation folder in ff57) so that I could manually enter the pages. Or any ideas?

All Replies (3)

So how did you loose the tabs to start with?

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.

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).

Firefox 56+ releases compress the files in the sessionstore-backups folder and sessionstore.jsonlz4 with LZ4 (.jsonlz4 instead of .js), so it is no longer easy to inspect them.

See also:

cor-el has pointed you toward the sessionstore-backups folder where you hopefully will find some useful files. Back up this folder somewhere safe.

Unfortunately, if you hadn't installed any updates for six months, you will not have the useful snapshot files Firefox makes at every update. But you might have something.

Note that Firefox 56+ uses the file extensions cor-el mentioned -- the lz4 indicates they are compressed. Firefox 55 and earlier used .js extensions.

Either way, you can use this tool on my website to preview the contents of older session files and, if helpful, save them as a page of clickable links for reference.

https://www.jeffersonscher.com/res/scrounger.html