I think you weren't notified because you didn't have an active Mozilla account? When I search back in time, I see as Tab Groups extension from Quicksaver -- is that the one? Step 1: Make a backup I don't know where the extension stored its data, so please make a backup copy of your entire currently active Firefox 56 profile folder. [[Profiles - Where Firefox stores your bookmarks, passwords and other user data]] Step 2: Build a time machine Actually, you just need to change your computer clock back four days to March 13, 2025. This could cause some other issues, but as an emergency starting point, it's what I've got. Step 3: Trigger Firefox to reverify your extension so they come back to life There is a date-time value in the prefs.js file (editable through about:config) which determines the time when Firefox next tries to re-verify your extensions. You may need to reset that value so Firefox doesn't wait until tomorrow. Here's how: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button accepting the risk. ''More info on about:config:'' [[Configuration Editor for Firefox]]. ''The moderators would like us to remind you that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future.'' (2) In the search box in the page, type or paste '''xpi-signature-verification''' and pause while the list is filtered (3) Right-click the '''app.update.lastUpdateTime.xpi-signature-verification''' preference and choose Reset to clear it (4) Do a normal exit/restart of Firefox, and within about a minute Firefox should reverify your extensions ---- Any progress so far? Next, Tab Groups has several different export options. In an issue thread for "Simple Tab Groups," a possible replacement you could try, they mentioned exporting per window in case a combined file didn't work. (Separately, if all these tabs are still open, I can describe how to use [https://www.jeffersonscher.com/ffu/scrounger.html my Scrounger tool] to generate a list of them as a page of clickable links. I don't know what effect the grouping might have on the list, i.e., whether it might be incomplete.)