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Restoring previous session issue

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  • Last reply by silia05

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I had multiple tabs open on firefox that I needed to check before closing. I had to restart my computer and so I closed the window, knowing that I could restore the session after the restart. However, after closing it, I realized there was another pop-up firefox window that I hadn't noticed - meaning, the multiple tabs window I closed wouldn't be saved for restoring later. I am wondering if there is a way to access that multiple tabs window now. I know I could go and check on history to collect my tabs, but these are tabs that I left open over months and it's almost impossible to find them by scrolling through months of history. Thank you!

I had multiple tabs open on firefox that I needed to check before closing. I had to restart my computer and so I closed the window, knowing that I could restore the session after the restart. However, after closing it, I realized there was another pop-up firefox window that I hadn't noticed - meaning, the multiple tabs window I closed wouldn't be saved for restoring later. I am wondering if there is a way to access that multiple tabs window now. I know I could go and check on history to collect my tabs, but these are tabs that I left open over months and it's almost impossible to find them by scrolling through months of history. Thank you!

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Note that on Mac closing Firefox can be more complicated because you can close all open windows, but keep Firefox running with the menu bar visible or minimized in the Doc.

Make sure to use "Quit Firefox" with all windows still open, especially if you want to use "Restore Previous Session". Otherwise check "History -> Restore Previous Session" and "History -> Recently Closed Tabs/Windows".


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 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).

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 look at this tool to inspect a compressed jsonlz4 sessionstore file.

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Thank you! That all is good to know for future issues. Unfortunately it didn't help with the current one. The session saved was the one tab pop-up window that I didn't know was there and not the multiple tabs one that I was hoping would be saved. I am guessing there is no way to find that one anymore.