Hi megus, Firefox normally only saves one previous session, so you can't go back two sessions. Firefox does also capture a snapshot from time to time when installing automatic updates, but that probably would be at least a week ago. Let's go through this:

Could you check whether either of these are available (not hidden or grayed out):

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

If they are missing or grayed, check either:

• "3-bar" menu button > Library > History > Recently Closed Windows
• "Library" toolbar button > History > Recently Closed Windows
• (menu bar) History > Recently Closed Windows

If that doesn't help...

Make a backup of your remaining session history files? Here's how:

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, find the Profile Folder row and click the "Open Folder" button. That will launch Windows' File Explorer and display the contents of your profile folder.

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

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

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 a tool on my site, then click Scrounge URLs:

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

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.

Next Steps

To avoid this post getting too long, let me know how that first set of steps goes.

OK, I think I'm close, but not sure what to do.

There are three upgrade files in the folder: All of which will contain the tabs I need.

How do I open one and restore that?

Thanks for your help!

Mike

You can copy a file from the sessionstore-backups folder to the main profile and rename the file to sessionstore.jsonlz4 to replace the current file with Firefox closed (make sure to backup the current sessionstore.jsonlz4).

Thanks! But I'm a real novice. Can you give me step by step details on how to do this?

You also can convert it to a page of clickable links using my Scrounger page if you don't want to wipe your current session (or just to have a backup).

That's located here: https://www.jeffersonscher.com/ffu/scrounger.html

Drop in the file and click Scrounge URLs. Usually finishes in less than 15 seconds. If it's still running after that, the tab might have crashed. Best to just close it in that case and try again in a new tab.

Once the list is generated, click Save List to generate an HTML download of the list for future reference.

That did generate the list, so I do know I can recover each of them, one at a time. I have 220

Is there an easier way to put a copy into it?

Here's the option cor-el was describing. This will replace your current session with the old one.

Manual Session History File Swap

(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, find the Profile Folder row and click the "Open Folder" button. This should launch a Windows File 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 -- a file named sessionstore.jsonlz4 usually appears in the folder.

Hide Session History Files

(3) Find these files and folders, right-click > Rename to hide them from Firefox

(A) sessionstore-backups folder => sessionstore-backupsOLD (ignore this folder for the rest of this process) (B) sessionCheckpoints.json => sessionCheckpointsOLD.json (C) sessionstore.jsonlz4 => sessionstoreOLD.jsonlz4 (doesn't always exist)

Introduce the file you want Firefox to use

(4) Copy/paste the file you want to restore

Right-click > Rename that file to sessionstore.jsonlz4

For example, previous.jsonlz4 => sessionstore.jsonlz4

(5) Start Firefox and it should read the swapped in session history 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

Any luck?

Thank! It took a while.

Would keep going back, but I finally was able to get it back up.

Thank you! Thank you! Thank You!