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

I renamed the sessionstore.jsonlz4 file and the sessionstore-backups folder. After restarting Firefox I have a new sessionstore-backups folder but no new sessionstore.jsonlz4 file. I still don't see the "restore previous session" in the drop down options.

I've added a screenshot of the drop down.

Thank you for your suggestion. What else can I try.

joeh7165 said

My drop down options no longer include the "restore previous session". I am at version 74.0

Hello joehh7165,

Probably a rhetorical question, but in Options => General, under "Startup": have you by any chance ticked the box " Restore previous session"  ?

Cause when that box is ticked, the "Restore Previous Session" option will be removed from the 3-bar menu ....

You don't see "Restore Previous Session" when you have Firefox set to restore the previous session automatically.

• Options/Preferences -> General -> Startup: "Restore previous session"

In that case Firefox will restore the session automatically, so there is no need to restore the session manually.

Does Firefox update the files in the sessionstore-backups folder during the session ?

You aren't using permanent Private Browsing mode (Always use Private Browsing mode; Never Remember History) or use "Clear history when Firefox closes" to clear the browsing history ?

Thank you for all your responses. I now have " Restore previous session" in the drop down box after changing the startup options and restarting Firefox.

The history was set to remember

joeh7165 said

I now have " Restore previous session" in the drop down box after changing the startup options and restarting Firefox.

    I'm glad that my question wasn't rhetorical after all !

tried what you guys said, i still lost my whole session.

tried what you guys said, i still lost my whole session.

Hello Paul,

Your problem may be different from the OPs ....

Maybe you'd better start a new thread, using this link :

https://support.mozilla.org/en-US/questions/new/desktop