If you check the History menu, does it have a Recently Closed Windows list? If it was not a private window, you may find your tabs by restoring a window there. (However, I run Windows, so I can never be sure how Firefox works on Mac.)

If the window is not restorable:

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:

(1) To open your profile folder...

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

• "3-bar" menu button > Help > More Troubleshooting Information
• (menu bar) Help > More 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 "Show in Finder" button. This should launch a Finder window listing the contents of your current profile folder. Sometimes Finder has the folder selected and you need to double-click into it to actually see the numerous files in there.

(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 where Firefox will ignore them.

(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

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?

Optional File Preview

The files can't be read by a text editor because they are compressed. To see what is in them, you can use a tool on my website:

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

Drag and drop a file from Finder onto the large white box, then click Scrounge URLs to generate a list. If it has useful stuff, archive the list as a locally saved web page by clicking Save List.

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.

Do any of the files have what you need?

Note that on Mac closing Firefox can be more complicated because you can close all open windows, but keep Firefox running with the menu bar visible or minimized in the Doc.

Make sure to use "Quit Firefox" with all windows still open, especially if you want to use "Restore Previous Session". Otherwise check "History -> Restore Previous Session" and "History -> Recently Closed Tabs/Windows".

Hey there thank you so much. Unfortunately the windows aren't any of the lost tabs, here is what I've got showing up: https://imgur.com/a/x3nXkXw

I'll complete the guide you've given me to see if I can find anything! Thanks so much I'll let you know how it goes following your guidelines.

Note that on Mac closing Firefox can be more complicated because you can close all open windows, but keep Firefox running with the menu bar visible or minimized in the Doc. Make sure to use "Quit Firefox" with all windows still open, especially if you want to use "Restore Previous Session". Otherwise check "History -> Restore Previous Session" and "History -> Recently Closed Tabs/Windows".

Yup this is exactly what happened. As said in my original post, I accidentally hit the red window close button instead of going to quit Firefox "properly". So Firefox was still "open" in the dock but the window (and all tabs) were closed. Also, as stated in my original post, there is no restore previous session or recently closed tabs that correlated to the tabs that were lost.

Do any of the files have what you need?

THANK YOU SOOOOOO MUCH!!! you've absolutely saved my bacon, I cannot begin to thank you enough for this, the lost session was saved in the first of the files that were in the sessionstore folder and your scrounger made it easy for me to restore the lost tabs, I am losing my mind with relief, thank you thank you thank you!!!