Hi,

You can try to restore via History (Alt + S) > Restore Previous Session, if it is active. Please also enter about:sessionrestore in the location (address) bar and check if tabs can be restored.

The version info @ https://addons.mozilla.org/en-US/firefox/addon/tab-utilities/versions/?page=1#version-1.1.2 states that it is compatible, though at least some reviews on the site differ. You can also try to Enable it in Tools (Alt + T) > Add-ons > Extensions (on the left). But before restarting please check the previous method.

That option appears to be greyed out. about:sessionrestore did not list anything. The Tab Utilities extension does not have an "Enable" button on my system, only a "Remove" at the moment.

Please try this: In Firefox, Help (Alt + H) > Troubleshooting Information > Open Containing Folder. This opens the Firefox Profile Folder. Copy the sessionstore.js and sessionstore.bak files to another place, Exit Firefox, delete these two files in the profile folder and copy and rename the sessionstore.bak to sessionstore.js from the backup to this folder (profile folder). Start Firefox and please also check about:sessionrestore. Please note that this may not help if the .bak file's size is smaller than the .js.

I followed the steps you provided, but it did not seem to fix my problem, or have any affect at all. My *.bak file is larger than the *.js file, for what it is worth. Also, I loaded the files into a text editor and there is no reference to the URL's that my app tabs had.

Note also that I use the Session Manager extension. I tried restoring an old session from about three weeks ago, and two of my app tabs came back. But around 4 are still missing. I have had the same set of around 6 or so app tabs for months. There is no apparent rhyme or reason as to why these two app tabs came back and the others did not when I restored the old session.

Have you tried just Re-pinning the App Tabs? Visit the sites, and Pin them again...

Yes, then pin fine, but its still a bug. I shouldn't loose them on an upgrade (and I hate to admit I don't remember which ones I had setup).

Is it Session Manager? You can check if any sessions are stored and try to restore. Please also see this.

Yes, it is Session Manager. That's what I tried above, when I got two app tabs back, but the others did not come back.

I just installed a preview version of Tab Utilities which does work with firefox 10 (Tab Utilities 1.2pre17). After the restart, all my original app tabs came back!

Glad you found a workaround, integrator. And thanks for posting it.