It is possible that there is a problem with the files sessionstore.js and sessionstore.bak in the Firefox Profile Folder.

Delete the sessionstore.js file and possible sessionstore-##.js files with a number and sessionstore.bak in the Firefox Profile Folder.

• Help > Troubleshooting Information > Profile Directory: Open Containing Folder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Deleting sessionstore.js will cause App Tabs and Tab Groups and open and closed (undo) tabs to get lost, so you will have to create them again (make a note or bookmark them).

• http://kb.mozillazine.org/Multiple_profile_files_created

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

• Help > Troubleshooting Information > Profile Directory: Show Folder

Hi Lea,

This also was happening to me. Every time I was closing and restarting firefox i was losing also all my tabs. I notice the problem was that sessionstore.js was been deleted each time I closed firefox. In fact I had some old sessionstore-<#number#>.js in my profile but they were dating from further. I tried renaming one of those before opening firefox and in fact i got old tabs restored, but then again after closing firefox the sessionstore.js was deleted.

Finally I find out the reason is that at the same time I had ask firefox to restore my tabs in the Privacy Tab from the Preferences Window I set Firefox to clean up my History each time Firefox close. So what this setting was doing was to remove the sessionstore.js each time I was closing Firefox. The workaround was to enable Firefox to remember my History.

In fewer words. Try to do this:

• Open Edit Menu > Preferences
• Change to the Privacy Tab
• Find the History part. There is a checkbox reading: "Clear history when Firefox closes". Make sure to uncheck that box.
• Close the Preferences window, then Firefox and restart again.

Hopefully this works also for you.