HI andirobinson,

The session that was lost is saved again each time you close and open Firefox. The about:sessionrestore page will open up the last session that was in Firefox.

There is a nice add on I use for this as well called Session Manager.

Please also see:

• Restore previous session - Configure when Firefox shows your most recent tabs and windows
• Back up and restore information in Firefox profiles

Since the tabs are no longer there, you can check the History Manager from the date the session was lost to find the urls. I hope this helps.

The session restore option was greyed out and still is. I have not had FF crash since this happened. But I really hope the next time it does, I am given the option to recover my previous session.

I regret to have to say that this is an abominable property of Firefox - losing the tabs from last session. It has happened to me more than once, and it's just happened again. I explored the 'Group your tabs' icon, didn't understand it - but found couldn't get out of it: I couldn't reverse my exploration - and before I knew it, ALL MY OPEN TABS HAD DISAPPEARED!

It's all very well citing add-ons that might preserve tabs, but no add-on is going to roll back time. Where is Firefox's programmers' sense of redundancy and safety?!?

FURTHER, the trouble with Firefox's multiple tabs session restore is that THE LOADED TABS DON'T ENTER THE HISTORY TRAIL. Unless they've been exposed, re-opened, during a session, they aren't remembered in history. Some tabs might not have been examined for weeks. If anything goes wrong with restore-last-session, ALL IS LOST! This is appalling software design. Firefox28

PhredE 11th May, 2014

Hi PhredE If the above information does not resolve your issue, please consider creating a new thread containing the specific details of your issue. Your issue may be different form this one.

Doing so will allow the Mozilla volunteers to give you solutions that are more helpful to you. This may help them to solve your problem faster and more efficiently.

Please, feel free to post the link to your thread on this thread for volunteers interested in assisting you.

Thank you.

@andirobinson Please try the [about:sessionrestore] page or see if the preference is locked in the profile folder. The easiest way to see if the preference is lockedHow to fix preferences that won't save or to reset Firefox Reset Firefox preferences to troubleshoot and fix problems

I am in the same boat as PhredE, where often a lot of my tabs haven't been reloaded in quite some time and so don't show up in my recent history, and as such can't be tracked down. I am currently on FF 30.0 and can't seem to restore. If I paste "about:sessionrestore" in the location bar, I get a blank list. I find it hard to believe that there seemingly isn't a single person working on FF who hasn't lost multiple sessions containing "old" tabs yet and decided there had to be a solution to it.

Hi microchipgirl, Thank you for your question, and sorry to hear that tabs are not showing up after Firefox is closed. There are a couple of places to check to find what may have caused this:

1. Do you have "Open tabs from last time" selected as the home page in you Options > Homepage
2. Did the browser crash before you opened Firefox? If so, the about:sessionrestore should open automatically the next time you open Firefox.
3. Do you have History set to remember all history in the Options/Preferences as well?

It is also possible to restore the session from last time: Restore the previous session from the history menu Is this portion greyed out?

Adding troubleshooting information to a new thread may help determine what is causing this issue. Since it is a different computer, you can check to see if there is an antivirus, or an add on that may be causing a session restore corruption.

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

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Multiple_profile_files_created

Deleting sessionstore.js will cause App Tabs and Tab Groups and open and closed (undo) tabs to get lost and you will have to recreate them (make a note or bookmark them if possible).

I can't say that that was much help, Guigs2 and cor-el :(

But first I should update cor-el's instructions for problem-checking: Hamburger^ > '?' > Troubleshooting Information. (Use Ctrl-F to find what you want in the page) Application Basics > Profile Folder > Show Folder [button] ^the three layered horizontal lines: Hamburger.

'Checking for problems' with the sessionstore files is easier said than done. Here's a snippet of one of mine: {"windows":[{"tabs":[{"entries":[{"url":"http://start.mozilla.org/en-GB/","title":"Mozilla Firefox Start Page","ID":2,"docshellID":5,"docIdentifier":2},{"url":"http://www.rlsdd.com/tutorials-ebooks","title":"RLSDD.COM - [ Tutorials & eBooks ] Archives ","ID":4,"docshellID":5,"docIdentifier":4}],"lastAccessed":1403401517892, "hidden":false,"attributes":{},"image":"http://ww

Huh?

As for examining profiles, the information there is nominal. And I certainly don't want to reset mine back to zero. I'd rather have what's wrong fixed in the current setup.

It seems to me that this problem - of disappearing sessions - is common and current in Firefox. It needs reworking with safety and redundancy in mind, IMO. Note that NASA did this long ago with three systems monitoring major functions, all voting. If there was an error, or a difference, in voting patterns, one opinion could be out-voted by the other two. Similarly here, one section of code believing that it has saved session data should be complimented by at least one other section writing a data set. The old FAT tables on our disks? There was always a backup in track 0. Two tables.

A maxim to live by: Trust, but verify.

PS Because Firefox has no redundancy in this regard, I regularly save my sets of tabs manually. I have a bookmark folder I named '! By Dates' (no appos; sits at top of alpha list), and I periodically save all tabs (it's back, BTW^) that are loaded, in a new sub-folder each time, named, for instance, 2014-07-04. Tedious, but ensures another level of safety.

^right-click any tab; choose Bookmark All Tabs...

PhredE 4th July, 2014

I have the same problem as the OP.

about:sessionrestore doesn't work either.

It just gives an apology for not working

I have the version 31, and so far the tab groups had worked fine. Firefox hasn't crashed lately and I shut it down properly. The crash history is negative too. Yet today when I reopened, I lost around 25-30 tabs in various groups that I was working on. The history is useless: I can't go through each and every page from last 3 months to see which ones I had saved for a re-check etc. The session restore doesn't have any options. I am dismayed by this turn of events. If only there was an option to restore tabs from even a day before!

Try:

• TabGroups Manager: https://addons.mozilla.org/firefox/addon/tabgroups-manager/

But is TabsGroupsManager fail-safe, cor-el? That seems to me to be the crucial issue here - reliability, robustness. Can I kill a Firefox process and expect TGM to bring back all the tabs I had open?

(Is there an automatic way to make links like yours open in a new tab?)

I still do it manually, as per my description on 4th July, above.

PhredE 11th August, 2014

The answer (to a manual fix, not an actual fix to the original bug) is here: https://support.mozilla.org/en-US/questions/983784 and they got the answer from here: https://bugzilla.mozilla.org/show_bug.cgi?id=668359

And the short version is this:

FIX:

Use a text editor and open the good sessionstore.bak is you still have it (make a backup of it first, of course.)

Assuming the file begins like this:

{"windows":[],"selectedWindow":0,"_closedWindows":[{"tabs":[{"entries":[{"url":"https:// ...

Remove the following chunk of text, starting with a close bracket and ending with an open bracket (highlighted in bold above):

],"selectedWindow":0,"_closedWindows":[

So you get:

{"windows":[{"tabs":[{"entries":[{"url":"https:// ...

Thanks shdwlynx, that pretty much did it. (A flaky fax modem caused a blue screen with extreme prejudice, and I lost all those tabs of things I was going to read or watch when I got around to it. I was surprised, after yet another "restore previous" earlier this week, I clicked on every tab to make it really open, but it didn't recorded to the history.)

Executive summary: if you can find a sessionstore.bak-datetime, each tab is a {entries: ... } in a comma-separated list in the tabs; paste them into the tabs list in a good sessionstore.js with Firefox not running.

In any case, what I can add is the following: I didn't have a useful sessionstore.bak, but in my profile directory (User/AppData/Roaming/Mozilla/Firefox/Profiles/9kad6vpt.default-1390310166560) there was a file named sessionstore.bak-20140917194002. (There were some other with bak-differentDateStamp that didn't work.)

It didn't start with ],"selectedWindow":0,"_closedWindows":[ so nothing to edit out. I tried renaming it sessionstore.js, not good enough.

So I copied it, and opened a new session with a couple of simple tabs, and closed. Now I had a good 'sessionstore.js', so I edited that, and at {"windows":[{"tabs":[<add the copied entries here>{"entries":[{"url":"http://www... (where that was the tabs I'd saved, one {entries:...}, each ) I copied all the similar items in the tabs list from the sessionstore.bak-xxx, starting with {"entries: for the first, and ending with the penultimate }, (the very last tab was just something that I had open when it crashed, so I lost it to keep the comma) and pasted that list at the start of the list of tabs, and saved that file.

When I next opened Firefox, the Restore Previous Session was available, and when I hit it I got everything back. I trimmed some, and following PhredE's advise I right-clicked on a tab and Bookmark All Tabs... into a dated subdirectory of a folder for that purpose, for the next crash before I have time enough at last to read all those tabs.

This has happened to me many times. It is very annoying and I have not managed to find a clear response on how to resolve. So here are my own directions. Hopefully others find this helpful:

Close out of Firefox

Go to the following file (obviously it will not be exactly the same file name but you get the gist):

C:\Users\Anne\AppData\Roaming\Mozilla\Firefox\Profiles\3dp6thze.default

locate the sessionstore.bak file

Your sessionstore.bak folder should be a large file (1000-3000KB - depends on how many tabs you have open, but if it is 1K, there is a problem). If it is small then this is a newer file without the history saved. You can double click on the file to open it and see if it has the code in the file. If you have lost this, you can right click the file and select "restore previous versions" to see if you can find a recent file (hopefully recent is better than nothing).

right click on the sessionstore.bak file and select copy

Then go to the top under organize and click paste (another version will be saved with "-copy" in the name). Do this as a fail safe in case something doesn't work when you open up Firefox again. You will still have a backup copy in the correct format. Otherwise Firefox will rewrite a new file when you close out of the session without your saved tabs.

delete the sessionstore.js file

Go back to the sessionstore.bak file and right click and rename this file to sessionstore.js

Open up firefox and go to History. The option to restore previous session should not be grayed out. Select and it should restore old tabs.

If this does not work, then your sessionstore.bak file wasn't good. Use the instructions above to restore an older file.

Good luck!

AOK1, your solution worked PERFECTLY!. Thank you so much!

The only thing I would add is this: when performing these tasks, make sure that Firefox is CLOSED, or else it just keeps recreating new sessionstore.js and .bak files and will only access the most recent ones; at least that's what happened to me. I ran into that a couple of times before figuring out that I needed to close FF first, perform the tasks, then re-open it. I only had one of each file type, so it was pretty straight forward.

With FF closed, I followed your directions and it restored my last session (with multiple tabs) which I lost on a Windows Update in the middle of the night.

Thanks again!!

Thanks jmjimmitchell! I am glad I was able to help. It is only because I have done it so many times and each time had a hard time finding the right instructions that I wanted to post this. I know that feeling of despair when you think you have lost all of your tabs. My first instruction is to Close out of Firefox, but I probably should have numbered the steps to make that clear since that is very critical.