Did you check the group tabs window?

• https://support.mozilla.org/kb/using-tabs-app-tabs-and-tab-groups

You can check the backups in the sessionstore-backups folder.

previous.js (cleanBackup: copy of sessionstore.js from previous session that was loaded successfully)
recovery.js (latest version of the sessionstore written during runtime)
recovery.bak (previous version of the sessionstore written during runtime)
 upgrade.js-<build_id> (backup created during an upgrade of Firefox)

You can copy a file from the sessionstore-backups folder to the main profile and rename the file to sessionstore.js to replace the current file (make a backup copy of the current sessionstore.js).

If you use the Time Machine then try to restore the sessionstore.js file from that backup.

• http://www.apple.com/support/timemachine/

First, I have no idea where to find the sessionstore-backups folder. It would be helpful to know that.

I did the “Refresh Firefox” thinking that would help me get back what I have lost. But it did not. And I am still not able to “restore previous session” - grayed out. Something very goofy is going on. And I am very frustrated and angry. This is taking HOURS of time to get back what I had before.

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)

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

Thank you for your reply. But I am still feeling very lost.

A couple days ago, following the problem noted above, I made a copy of the Profile file and saved it to my desktop. I lost my tabs on around June 22. But the most recent file I can find in this profile copy is upgrade.js-20150525141253 (6/3/15). So how do I have any chance of finding all the data I have lost?

I am sending you a screen capture of the folder that I refer to above (a saved version from a couple days ago). What am I missing. How do I get to a backup that will allow me to salvage all that has been lost???

I also checked my Apple Time Machine - but the farthest it goes back is yesterday and I need at least one more day back to find what I am missing.

Restoring upgrade.js-20150525141253 by copying the file to sessionstore.js will restore the tabs that you had when this file got created when you last updated Firefox.

jdavid17 said

I had been working on a project with several tabs. I went to "Group as Tabs" to get better organized. Poof - all my tabs were gone. And the normally helpful "Restore Previous Session" was gray - not available. I am so very frustrated. Am on deadline - I did not have this time to waste on trying to rebuild everything. What the heck is going on? And how do I get everything back???

WORSE BY THE WEEK!! For the second time in the past two weeks, I have lost ALL TABS, ALL PIN TABS. If you are wanting to drive me batty, you are succeeding. And I am in the middle of a deadline - do not have time for this. Either Mozilla get's there acts together, or I will be forced to find another more reliable browser. THIS IS CRAZY.

All I knew that I did was update Adobe Flash. It was right after that when everything vanished. And there was not a way to restore previous session.

Here is what I lost: - All pinned tabs - All tabs

I have attempted today to find my backup file. Can't even find it. My HD > Library > Application Support > (There is no Firefox listed) My HD > Library > Application Support > Mozilla > Extensions > (There is no backup folder. There are three folders but unclear what they are.)

So in two weeks, I have lost TWICE All tabs, all pinned tabs, all tabbed groups.

PLEASE GET YOUR ACT TOGETHER. This kills me. There has to be a quicker, easier way to recover this sort of thing. Right now, I am not finding it. HELP!!