Delete the files sessionstore.js [2] and sessionstore.bak in the Firefox Profile Folder.

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

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.
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).

See also:

• [1] http://kb.mozillazine.org/Session_Restore
• [2] http://kb.mozillazine.org/sessionstore.js

I can not open Firefox to access the profile. Can I access profile file in internet explorer?......

See:

• https://support.mozilla.com/kb/Profiles#How_to_find_your_profile
• C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile>\

The "Application Data" folder in XP/Win2K and the "AppData" folder in Vista/Windows 7 are hidden folders.

• Use %APPDATA% in the File name field or make sure that you see hidden folders.
• http://kb.mozillazine.org/Show_hidden_files_and_folders

• Go to: Control Panel > Folder Options > "View" tab, and under "Hidden files and folders", select "Show hidden files and folders"
• To see all file extensions uncheck the box "Hide extensions for known file types"

I seem to have this problem too, the thing is, its not about the session stored. Mine seem to have something to do with browser not being able to load enough images, and just freezes. Related? https://support.mozilla.com/sv-SE/questions/877758

This probelm was very frustrating and too difficult to fix. I changed browsers to Chrome, wow much faster and super easy to use. Sorry Firefox, you have been my fav. for may years., but it is time to move on.......delete program? yes. Are you sure? YES