This can be a problem with the file sessionstore.js and sessionstore.bak in the Profile Folder

Delete sessionstore.js and sessionstore.bak in the Profile Folder

If you see files sessionstore-##.js with a number in the left part of the name like sessionstore-1.js then delete those as well.

See:

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

This did not work. I followed all the steps and that year-old session still opens every time I start up Firefox. I love Firefox, have used it for several years now, but this is intolerable. I cannot save any useful work at this point.

Are you using any extensions like Tab Mix Plus that have their own implementation of session restore?

An older session can only be restored if that session is saved in the profile folder. If you remove sessionstore.js and sessionstore.bak then Firefox can't restore older sessions. If there is an extension that uses its own files then that isn't affected.

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the add-ons is causing the problem.

• Don't make any changes on the Safe mode start window.

See:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

There wasn't a sessionstore.bak to delete, only sessionstore.js, which I deleted. I have occasionally had a more recent session restore when I open Firefox but periodically this year-old sessions has popped up instead, and for the past two weeks it is the only session that restores.

I am using Colorful Tabs, but nothing called Tabs Mix Plus. I will try starting it in safe mode to see what happens, but I don't understand why this has been a periodic problem in the past and/or why it has gotten worse recently. You would think it would be all or nothing.

That year-old session appears in safe mode as well.