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Restoring previous sessions

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I like to save a copy of my session store backup file every few days because Firefox will randomly forget about half of my previously closed windows. It happened again today so I tried to restore my session from the 25th. I closed Firefox, deleted the 8/29 previous.jsonlz4, recovery.baklz4 & recovery.jsonlz4 files & pasted the ones from 8/25 into the sessionstore backups folder. When I restarted Firefox instead of using my 8/25 session files it replaced them with the ones from 8/29. I've never had a problem restoring previous sessions in this manner until today. Is there anyway to fix this or are all of my previous sessions backups worthless now?

I like to save a copy of my session store backup file every few days because Firefox will randomly forget about half of my previously closed windows. It happened again today so I tried to restore my session from the 25th. I closed Firefox, deleted the 8/29 previous.jsonlz4, recovery.baklz4 & recovery.jsonlz4 files & pasted the ones from 8/25 into the sessionstore backups folder. When I restarted Firefox instead of using my 8/25 session files it replaced them with the ones from 8/29. I've never had a problem restoring previous sessions in this manner until today. Is there anyway to fix this or are all of my previous sessions backups worthless now?

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Use one of these to close Firefox if you are currently doing that by clicking the close X on the Firefox Title bar, especially if you have multiple windows open to prevent losing tabs in unnoticed windows.

  • "3-bar" menu button -> Exit (Power button)
  • Windows: File -> Exit
  • Mac: Firefox -> Quit Firefox
  • Linux: File -> Quit

Note that Firefox needs to be closed when you replace sessionstore.jsonlz4 with an older backup copy. Also make you you do not use Sync as that can interfere.

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 with Firefox closed.

  • make sure to backup the current sessionstore.jsonlz4

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