Usually Firefox will attempt an automatic crash recovery for a regular (non-private) session. Are you saying Firefox did a crash recovery but several windows were missing? Or Firefox did not automatically restore and instead you did it manually?

If these items are hidden or grayed out --

• "3-bar" menu button > Restore Previous Session
• (menu bar) History > Restore Previous Session

-- then try:

• "Library" toolbar button > History > Recently Closed Windows (and within each restored window, Recently Closed Tabs)
• (menu bar) History > Recently Closed Windows (and within each restored window, Recently Closed Tabs)

By default, Firefox remembers and allows you to restore up to 3 closed windows.

If that doesn't help...

Firefox creates numerous session history files, but because session history is only for the immediately previous session, it is unfortunately too easy to lose it. Could you start by making a backup of your existing session history files? Here's how:

Do not exit Firefox, or if you closed it, don't re-open it.

(1) To open your profile folder...

If Firefox is still running:

You can open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" Help > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Open Folder" (or "Show in Finder") button.

If Firefox is closed:

Type or paste the following into the Windows Run dialog or the system search box and press Enter to launch Windows Explorer:

%APPDATA%\Mozilla\Firefox\Profiles

In that folder, do you see a semi-randomly-named folder? If so, click into it. If you find multiple such folders, find the one that was most recently updated.

(2) Copy out session history files

In your profile folder, double-click into the sessionstore-backups folder. Save all files here to a safe location such as your Documents folder.

(3) What files did you find?

The kinds of files you may find among your sessionstore files are:

• recovery.jsonlz4: the windows and tabs in your currently live Firefox session (or, if Firefox crashed at the last shutdown and is still closed, your last session)
• recovery.baklz4: a backup copy of recovery.jsonlz4
• previous.jsonlz4: the windows and tabs in your last Firefox session
• upgrade.jsonlz4-build_id: the windows and tabs in the Firefox session that was live at the time of your last update
• various .js files from Firefox 55 or earlier

Could you take a look at what you have and the date/time of the various files to see whether you think any of them would have the missing tabs?

To preview the contents of a file, you can drag and drop it onto this page, then click Scrounge URLs: https://www.jeffersonscher.com/res/scrounger.html

That tool is on my site, so please let me know if it doesn't work for you.

I see a session that could be it, but I'm wondering, if the session was created in February, does that mean the session could have the tabs up to now of March 16th or would it have to be the proper recent date for the tabs recovery? As I have no files in Sessionstore-backups that are from earlier enough today to be the right time for all tabs session it seems. As they were definitely overwritten by the BSoD crash and having to reboot into Firefox using the "Restore last session" on the "2 tabs portionate recovery." Hopefully there is another way than having to guess through all that history I have.

I have: recovery.jsonlz4, recovery.baklz4, upgrade.jsonlz4, previous.jsonlz4, but they are all from February or since the recent crash late of today, but nothing in between for the recovery JS files, however there are other JSon Files but they don't appear to be recovery sessions, so much as recent URLs no different than going through history Sidebar. Hopefully there is another way, there has to be more options...

I restarted Firefox from a past successful session recovery, but suddenly BSoD was getting very annoying, and reboots for me take a long long time. So I decided to boot up in Safe Mode and update security along with cmd CHKDSK /f, without opening Firefox this time. I then rebooted into normal mode without a single crash in between all this, and when I started up Firefox with the expected "Restore Session" I only had 2 tabs as it failed to make the full recovery which I don't get, possibly a rare bug that doesn't happen often, but am hoping for a solution here haha! I feel this shouldn't have surprisingly gone so wrong, and has to be another way than to manually go through 4 months of history. The worst part is, I was going to be finished today, but now may take longer if no other solution...

Do you think Windows might have done a system restore to an earlier date? That could explain why the contents of the sessionstore-backups got rolled back to February.

Please try this:

(1) Set Windows to show hidden files and folders:

https://support.microsoft.com/en-us/help/14201/windows-show-hidden-files

(2) Download and run one of these programs:

• ShadowExplorer: http://www.shadowexplorer.com/
• System Restore Explorer: http://nicbedford.co.uk/software/systemrestoreexplorer/

Within the most restore points shown in the program, you can explore along this path to see whether you can find a more recent shadow copy of your profile with fresher files in the sessionstore-backups folder:

\Users\your-user-name\AppData\Roaming\Mozilla\Firefox\Profiles\

Oh my goodness you are a GENIUS! Shadow Explorer has a recovery.bak and a recovery.Json from March 6th of recent! I just don't know what to do with them from this program to safely extract it for the tabs. What will I do from here with them in the Shadow Explorer program?

Also my apologies for the late response, but my Laptop crashed again, and I decided to have a snack cuz it takes awhile to reboot.

I think ShadowExplorer lets you Export or Copy a file to a safe location, such as your desktop. Then this is the procedure to put it where Firefox will find and restore it.

The general strategy for restoring an old session history file is:

(A) Identify the file you want to use from your backup -- you already did this step

(B) After exiting Firefox, hide the sessionstore.jsonlz4 file and the sessionstore-backups folder from your latest session

(C) Set up the old file in the profile folder as sessionstore.jsonlz4 or, for older .js files, sessionstore.js, then start Firefox and Restore Previous Session

For (B) and (C), in more detail:

(1) From inside Firefox, open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" Help > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Open Folder" button. This should launch a Windows Explorer window listing the various files and folders in your profile.

(2) Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > "power" button Exit
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup -- these changes should occur:

• recovery.jsonlz4 is moved from the sessionstore-backups folder to the main level of the profile folder and renamed to sessionstore.jsonlz4
• recovery.baklz4 is deleted from sessionstore-backups

Once Firefox has stopped updating things, while viewing that main level of the profile folder:

(3) right-click > Rename the sessionstore-backups folder to sessionstore-backupsOLD so Firefox doesn't try to use those files (it will create a new one)

(4) right-click > Rename the sessionstore.jsonlz4 file to sessionstoreOLD.jsonlz4

If you see an older sessionstore.js or sessionstore.bak file, move it somewhere else or delete it.

(5) Copy the old file you want to use [recovery.jsonlz4] and paste it into the current profile folder (please don't move the original in case this takes multiple tries)

(6) right-click > Rename recovery.jsonlz4 to sessionstore.jsonlz4

(7) Start Firefox and it should read the swapped in sessionstore file and restore whatever was in the substitute file; if you do not have Firefox set to restore your previous windows and tabs automatically, use Restore Previous Session.

Success?

Alternately, you can convert the old session file to an HTML links document using

https://www.jeffersonscher.com/res/scrounger.html

and just open the ones you want from that as needed.

Step A: we established the recovery file as recovery.jsonlz4, but earlier is stated it only recovers last session, or does it restore the session for the date the file was created? Thus would use this as the old file to make the new session restore.

Step B: sessionstore.jsonlz4 isn't in my mozilla backup main page or in the files of it, however it may be in another mozilla main page file list, which would mean hiding it wouldn't be necessary since it's already located elsewhere? However the sessionstore-backup is there in the main profile page, which I can hide, but I don't know what you mean by hide it from "latest session." What is the "latest session" in this case? It confuses me cuz were talking about files and folders, so don't see what it's implied to, unless it's just hiding them in general cuz is necessary, and of course is after already exporting the Shadow Explorer "recovery.jsonlz4" file to random Desktop Folder for importing into Mozilla profile main page, is this right?

Step C: You say to setup the old file (implying old "Recovery.Jsonlz4 file" from Shadow Explorer) into the profile folder, but is this implied to the main page of all the files and folders, by which would rename the "recovery.jsonlz4" to "sessionstore.jsonlz4? Thus with Firefox closed from Step B would now open Firefox for the session restore?

I had to take my time with this cuz I don't want to mess up. I am terrible at implications at things I'm new too, so have to break the implied portions down into the direct obvious statements, sorry about that hahah.

The text of (B) and (C) is just an overview. Please follow the numbered steps for how to do (B) and (C).

I see now haha, sorry this is my first time, plus so much is happening it's been a little difficult on my end. You're much faster at understanding this for sure haha! The shock from tabs suddenly lost after multiple success restorations was so bad, it gave me ideas for my studies as I'm learning new things which took time to think over. I'll try this out later tonight or tomorrow, and understand it perfectly. I'll come back here to thank you after trying the solution out you have provided, thanks!

Holy SMOKES it WORKED HAHA! Thanks for that and I feel truly blessed for your support. I was so worried I lost it all, but the old recovery gave me everything back, more than I thought. All tabs are back and thank goodness "Shadow Explorer" worked because "Nicbedford" looked complicated!

Not to mention it gave the Tabs back with the previous Tabs still there for each Tab, so that's awesome. This is the ultimate SOLUTION!

I ended up bookmarking this page LOL!