Does Firefox list any closed windows on either of these menus that you can re-open: * "3-bar" menu button > History > Recently Closed Windows * (menu bar) History > Recently Closed Windows If not... you probably can't get all your tabs back, but depending how long you keep tabs open, you might be able to recover some of them. Step 1 is to get into your active profile folder. Here's how: 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 "Open Folder" or "Show in Finder" button. This should launch a Finder window. Either you will see a huge list of files, or you might see one or two icons with partially random names, like abcd1234.default, with one icon selected. Double-click that icon to list the folder contents. '''Check the 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. 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 Sometimes you can tell from the last modification time which one is most likely to have your missing tabs, but not always. '''''Optional File Contents Preview''''' These compressed files are a pain to view, so I created a tool on my website to list out their contents. If you want to try that, you can drag and drop it onto the large box on the following page, then click the "Scrounge URLs" button: 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. Do you see anything promising?

If you use the Time Machine or other backup then try to restore file(s) from this backup. *https://support.apple.com/guide/mac-help/restore-files-mh11422/mac *https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile