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Help Request: Recovering/Syncing a lost session

  • 3 回覆
  • 0 有這個問題
  • 5 次檢視
  • 最近回覆由 cor-el

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Good morning, good afternoon or good evening to whoever is reading this,

Yesterday in the early hours of the morning my Firefox updated, and after it restarted following this I lost my session - I have tried to restore my previous session, and sync to the previous session, but both have been unsuccessful. How can I restore that session?

Synchronise options show two sessions - image attached - the new session (red) following the reboot, and the old session (green) that I want to go back to, how can I do this?

I'd really appreciate any advice.

Thank you very much.

Best regards, Sarah

Good morning, good afternoon or good evening to whoever is reading this, Yesterday in the early hours of the morning my Firefox updated, and after it restarted following this I lost my session - I have tried to restore my previous session, and sync to the previous session, but both have been unsuccessful. How can I restore that session? Synchronise options show two sessions - image attached - the new session (red) following the reboot, and the old session (green) that I want to go back to, how can I do this? I'd really appreciate any advice. Thank you very much. Best regards, Sarah
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所有回覆 (3)

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You can't recover a session via Sync. However Firefox normally creates an upgrade.jsonlz4-<build_id> file when it updates to a new version that should have the session from before the update.


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

In case of issues also see:

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Hi Cor-el,

Thanks for your quick reply.

cor-el said

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.

There is a "upgrade.jsonlz4-20220718155818" file in the sessionstone-backups folder from the time of the update - when you say copy it to the main profile (and rename it) do you mean placing it in the .default parent folder, or elsewhere?

Thank you very much.

Best regards, Sarah

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You need to close Firefox to make this change and in that case should Firefox create sessionstore.jsonlz4 at the main level in the Firefox profile folder (i.e. the location where you see the sessionstore-backups folder). You need to replace this sessionstore.jsonlz4 with the upgrade.jsonlz4 file.

Just to be sure that is has the tabs you are after, you can look at this tool to inspect a compressed jsonlz4 sessionstore file.