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  • 4 replies
  • 1 has this problem
  • Last reply by Bithiah

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Three times now I have lost over 150 open tabs on Firefox and have spent hours trying to recover them but to no avail.

I have tried absolutely everything I have read in multiple support posts such as clicking on the 3 lines, trying to go into history, etc. The best I can do is go into my history to see thousands of website that I have been to in the past several months, but seemingly no way to restore only the 150 tabs that I had open.

Several of the posts refer to trying to find previous files with names in them such as "session..." and "json..." etc. but I cannot find any of these files on my hard drive.

MESSAGE TO FIREFOX DEVELOPERS: Please please please add an option to load a previous set of tabs that were open a week or two ago. Not an option to open the websites I was on, but the actual saved tabs. Very frustrating!!!!!! It's not reasonable to expect someone to go through 3,000 web pages in the history to find the 150 that I opened and left opened for a reason. A couple of hundred hours of my time in research down the drain.

Please help. I'm using the latest firefox browser on Windows 7. Thanks.

All Replies (4)

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Hey there!

I think you should send a feature request to the devs. To do so please see:

Hope I helped!

Kind regards,


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Hi Tom, Firefox has an option to restore your previous session. Given that you're already opened Firefox to go through your history, your previous session is not the one with 150 tabs, but should this happen again, try the instructions in the following article, and see if they help: Restore previous session - Configure when Firefox shows your most recent tabs and windows

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Hi Tom, I'm sure you have seen this in other threads, but for quick reference:

(1) Session history files are stored in your currently live profile folder. This article has the steps to open that folder: Profiles - Where Firefox stores your bookmarks, passwords and other user data.

In your profile folder, you should find a subfolder named sessionstore-backups. I suggest making a backup copy of all the files in that folder in a safe location (for example, in your Documents folder) before doing anything else.

(Please note that .jsonlz4 and .baklz4 files are compressed and you will need to decompress them if you want to see their contents. More details in the "Previewing Session History Files" section below.)

(2) Sometimes users end up with a new profile that doesn't contain their data from their earlier profile folder. If you lost settings at the same time you lost your tabs, you can check other profiles. Here's how:

First, exit out of Firefox normally (from the menu) and do a normal shutdown and restart of Windows to free up any locked files and resolve any transient privilege issues.

Profile Manager Page

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

This page should list at least one profile and could list many. (Each profile has two folders and one or more buttons. Do not use any Remove buttons!)

The profile that Firefox is currently using will have this:

This is the profile in use and it cannot be deleted.

Do you have any other profiles listed on this page? If so, you can check whether you were using one of them recently by clicking the Launch profile in new browser button in its section.

If it isn't what you want, simply close that new window.

If it IS what you want, back on the about:profiles page, click the Set as default profile button for that profile so Firefox uses it automatically at the next startup.

Previewing Session History Files

The files you usually find in the sessionstore-backups folder 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

Usually the recovery and previous files are too new to have missing tabs, but you can check their timestamps and sizes to make a guess. The upgrade files from 91.0.2, 91.0.1, and 91.0 could have valuable here.

To preview the contents of a file, you can drag and drop it onto the box on this page on my site:

The scripts in the page should decompress the file, and the box should contain session data that starts off like this (your URLs probably will be different than mine):


To list out the URLs in a more useful way, click the Scrounge URLs button.

If you don't get a list within 15 seconds, that probably means the script is caught in a loop. You may need to close the tab to avoid a tab crash and then try again in a new tab.

If you get a useful list, use the Save List button to archive it as a web page of clickable links for future reference, in case no other approach is successful.

Anything promising so far?

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Hey there!

If your problem is solved, please mark a solution so that others can see this thread is solved. Thank you in advance!

Kind regards,