Hey djbluntmagic. I think this guide will help you.

Make sure that you do not run Firefox in (permanent) Private Browsing mode.

• https://support.mozilla.org/kb/Private+Browsing

• Tools > Options > Privacy: Use custom settings for history
• Deselect: [ ] "Always use private browsing mode"

In case you are using "Clear history when Firefox closes":

• do not clear the "Browsing History"

• Tools > Options > Privacy: History: [X] Clear history when Firefox closes > Settings
• https://support.mozilla.org/kb/Clear+Recent+History

Note that clearing "Site Preferences" clears all exceptions for cookies, images, pop-up windows, software installation, and passwords.

"Tools > Options > Privacy: History: [X] Clear history when Firefox closes > Settings " This isn't an apparent setting in the path you indicated

@openjck Like I said, I already have this feature set

Use "Use custom settings for history" to see all history settings

• Tools > Options > Privacy > Firefox will: "Use custom settings for history"

• Press the F10 key or tap the Alt key to bring up the "Menu Bar" temporarily if the menu bar is hidden.
• Use "Firefox > Options" instead of "Tools > Options" if the menu bar is hidden.

Nah, I've got it on "remember history."

Did you check the settings for "Clear history when Firefox closes" ?

See:

• https://support.mozilla.org/kb/Options+window+-+Privacy+panel

Well it wouldn't do that, would it, if I've got it on "remember history."

Can you please just check those settings to verify that you aren't clearing data?

The "Use custom settings for history" selection allows to see the current history and cookie settings, but selecting this doesn't make any changes to history and cookie settings.

You can check for problems with the sessionstore.js and sessionstore.bak files in the Firefox Profile Folder that store session data.

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

Well, verifying that I have it on "remember history" constitutes checking, since the settings under custom wouldn't be in effect , but OK, I checked, and the setting isn't selected, and followed the ensuing instructions.

Any ideas other than the obvious?

There are at least two conditions required:

1. you need to keep history, so verify that you still have those pages in history after restarting Firefox if you haven't removed them manually yourself
2. a sessionstore.js file needs to be created that has stored the page from that previous session, so verify that you have this file with a correct time stamp

• https://support.mozilla.org/kb/Session+Restore

You can also check if there are recently closed tabs or windows with pages from that previous session.
You can also try to kill Firefox via the task manager to simulate a crash to see if that brings back the tabs.

Also verify that session restore is enabled.

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

Well thanks for the help. I didn't change anything but it's working again anyway, so I guess I'll be back if it acts up again.