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"

Thank you for your response, but I do not have that option checked.

Check that session restore is enabled and working.

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

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

My Options > General > when Firefox Starts setting is "Show my windows and tabs from last time" as previously stated (see attachment too). In the profile folder when Firefox is shut down I do not have any sessionstore.js, .bak or duplicate numbered sessionstore files.

I even tried restoring a sessionstore.bak from a backup, renamed the extension to .js and brought up Firefox. It had all the startup tabs that were recorded in the old .bak file. But once I shut down Firefox and started it up again, it only showed my homepage tab again.

I've read all the links you sent and it is unclear what else I should be checking or doing at this point. Session restore is enabled but not working as far as I can tell.

Is there a procedure where I can manually change a preference entry, like modifying Firefox's internal registry? Is that worth a try? I remember being given those instructions (in fact, involving tab restore sessions!) back in Firefox v4 or thereabouts.

If that won't work would reinstalling Firefox be worth a try? Will a reinstall save all of my bookmarks and Sync data? I would not want to lose any of those bookmarks or links to my other syncing platforms.

Should I reboot my PC and see what happens? (Just trying to get this simple but useful feature working again.)

Thanks for your continued attention here. It is quite a mystery that this suddently started happening after the 18.0.1 update.

You can try to rename or delete the prefs.js file and possible numbered prefs-##.js files and a possible user.js file to reset all prefs to the default values.

• http://kb.mozillazine.org/Preferences_not_saved
• http://kb.mozillazine.org/Resetting_preferences

• https://support.mozilla.org/kb/Preferences+are+not+saved
• https://support.mozilla.org/kb/Resetting+preferences

You can create a new profile as a test to check if your current profile is causing the problems.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer some files from an existing profile to the new profile, but be careful not to copy corrupted files.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Success. I restored a prefs.js file from a few days ago. I then made 1 change in it to make it current (Tools > Options > Content > Block Pop-up windows > Exceptions, deleted 1 url). Tabs are now saved across sessions.

Strange there was no change to: Tools > Options > General > When Firefox Starts > Show my windows and tabs from last time AND no change to: Tools > Options > Privacy > uncheck Always Use Private Browsing Mode.

. . .but I never argue with success! Thanks for your suggestions and your time today that (mysteriously) led to a resolution.

You're welcome.

Which changes did you make to the prefs.js file?

I had 2 entries in the Block Pop-up windows Exceptions in the backup prefs.js file and deleted 1 of them. That could not have had anything to do with Session Restore tabs working again. I just needed to bring the backup prefs.js file up to date for my needs.

Found the trick folks - - don't "clear history when firefox closes".

I actually had some custom settings set in TOOLS:OPTIONS:PRIVACE - under History - and the last check box was checked and that was keeping firefox from logging or caching or whatever it does so the last tabs I had opened did not reload after exiting.

Adios. Distilled

Firefox is getting worse and worse every "update". I cant tell you how many times I lost my tabs and it's impossible to get them back. There's an add-on called FVD speed dial for managing most active sites you use...but it does absolutely nothing

I may be in the wrong place here but following this thread as it related to my own inquiry. It does seem from the responses above like awful lot of internal steps to go through for a simple process.

My question in followup - my tabs will remain (most of the time) when closing and re-opening firefox, but they do not update automatically when opening firefox, which makes saving them kind of pointless - so I am trying to determine what is missing to ensure they open with current information?

I hope this helps! http://mzl.la/128veEp