You can copy a file from the sessionstore-backups folder to the main profile with the Firefox application closed and rename the file to sessionstore.js to replace the current file (make a backup copy of the current sessionstore.js).

Thank you, cor-el. Your repsonse was vague - what is the "a file" you mention? All the files in my backups folder were too small to be the one I needed. However, I found the correct one in my OLD profile folder ( 9f5baooc.default ) - the one that existed before the incident, and now has been replaced with a new one ( d0a3p5tm.default-1436646365883 ). When I used the correct one, and followed your advice, I got my old tabs back.

I have to reopen this thread, since I lost all my tabs again this morning. This time, I looked everywhere for a sessionstore.js file that I could use to restore yesterday's tabs. But the latest one I could find was the same one I used back in July, so I had to use that one. This is most unsatisfactory, since a lot has changed in the past month.

Can anybody tell me where the latest Profiles are stored, so I can bring back the tabs from yesterday? I thought I checked everywhere, but maybe there is a location that I didn't find.

If you have already updated to Firefox 40 then you might have an upgrade.js file in the sessionstore-backups folder.

The sessionstore.js file in the profile folder is still used to store session data, but is only present when Firefox is closed. The sessionstore.js file is created from recovery.js when you close Firefox and is removed and copied to previous.js when you start Firefox.

You can backup the session files in the sessionstore-backups folder in the Firefox Profile Folder to make sure not to lose possible important session data.

previous.js (cleanBackup: copy of sessionstore.js from previous session that was loaded successfully)
recovery.js (latest version of the sessionstore written during runtime)
recovery.bak (previous version of the sessionstore written during runtime)
upgrade.js-<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.js to replace the current file (make a backup copy of the current sessionstore.js).

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Thanks, cor-el. I understand what you're saying, but it doesn't help. There is nothing in the Profiles folder that is dated yesterday, so I can't get back the tabs I had yesterday. The best I can do ( I already did it ) is to get back the tabs I had on July 12.

You can check if there is a previous version of the sessionstore.js file available.

• Right-click: Properties > Previous Versions

• http://windows.microsoft.com/en-US/windows7/Previous-versions-of-files-frequently-asked-questions

Thanks again, cor-el. But I already checked for previous versions, and there are none. I guess somehow they got lost. But I don't understand how, since System Protection is supposed to automatically create previous versions once a day.