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I am trying to restore my session and got an unresponsive script message. Upon stopping the script, I can no longer restore my session. How do I restore session

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After a crash, I tried to restart firefox. I got the usual [!]Restore Session window, but there was an unresponsive script warning. I clicked "continue," and I got another warning. I then clicked "stop script," and now the window is frozen. I cannot access "restore session" in my History menu and I cannot seem to get anything in the restore session window to work. How do I restore my previous session? I checked my security settings on my history preferences and my custom history settings are not set to "always use private mode." I am worried about losing my restore data by restarting the browser. Do I need to resume the script? Or can I restore my session from a different window?

After a crash, I tried to restart firefox. I got the usual [!]Restore Session window, but there was an unresponsive script warning. I clicked "continue," and I got another warning. I then clicked "stop script," and now the window is frozen. I cannot access "restore session" in my History menu and I cannot seem to get anything in the restore session window to work. How do I restore my previous session? I checked my security settings on my history preferences and my custom history settings are not set to "always use private mode." I am worried about losing my restore data by restarting the browser. Do I need to resume the script? Or can I restore my session from a different window?

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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

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You need a copy of previous.jsonlz4

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.