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).

See also:

• http://kb.mozillazine.org/Session_Restore
• http://kb.mozillazine.org/sessionstore.js
• http://kb.mozillazine.org/Multiple_profile_files_created

Thanks cor-el. Will do and see how it works from here on. again thanks.

You're welcome

Well, that didn't help. Computer just crashed and the session that was restored was the one from yesterday after I did the above and closed and restarted firefox. So it's only storing session info when you close and exit firefox now, apparently.

It sounds that Firefox crashes before saving the session to sessionstore.js on your hard drive.

Using the "Show my windows and tabs from last time" setting is a more reliable way to restore session data.

• Tools > Options > General > Startup: "When Firefox Starts": "Show my windows and tabs from last time"

That's how mine is set. Didn't FireFox save tabs on a frequency rather than just when closing or crashing before? Sure seems like it only saves tabs now when you manually close it.

I just checked the browser.sessionstore.interval and it's set at 60000. I've never changed this and assume it must be the default level. As I understand it the value is defined in milliseconds, so 60000 is 60 seconds or every min. Mine is clearly not saving session information on this interval.

Well. it's clear something in my R12 of FF is broke. On another computer I use the "sessionstore.js" file is updated every min. like clock work while FF is running, while on this machine it only saves it on exit. I'll see if I can find any other info setting that might explain it.

OK, looks like the "browser.sessionstore.resume_from_crash" was set to false, and should have been true. It seems to now be storing session info every min as before. Wonder if one of the crashes/updates caused this?

Well, after closing and restarting FF the value went back to false and it's broke again. Wonder what's setting it to false?

It saves and restores sessions OK after a manual close regardless.

See:

• http://kb.mozillazine.org/Preferences_not_saved
• https://support.mozilla.org/kb/Preferences+are+not+saved

Ok, it looks like something is setting "browser.sessionstore.resume_from_crash" to false on startup, so I'm suspecting an add-on god rough or such.

Even after re-creating and manually editing the prefs.js file when FF starts it gets reset to false. So I'm going fishing.

Well I've tried everything I can and when you close it and re-open FF, the "browser.sessionstore.resume_from_crash" keeps getting set to false, and indicates it's "user set".

So something in my configuration/add-ons is causing it. Any Clues?

Found the culprit. "https://support.mozilla.org/en-US/questions/763161#answer-115393"

Apparently I have a file called user.js that was created somehow on 5/13 with the two following lines: user_pref("network.protocol-handler.warn-external.dnupdate", false); user_pref("browser.sessionstore.resume_from_crash", false);

Removing this file fixed it! thanks for the help.