Hi Wolfgang, each profile has a set of session history files. If you restore your previous session windows and tabs every time you start Firefox, there is a chance that even after a week, you data might be recoverable. But unfortunately, no guarantees. Hmm, where to start. First, I assume you have already checked the "List All Tabs" button in each profile to see whether the Recent Tab Groups section allows restoring any of the missing groups (the closed groups have an empty square, open groups have a filled square): <blockquote><img src="https://assets-prod.sumo.prod.webservices.mozgcp.net/media/uploads/images/2025-09-16-16-56-35-f12307.png"></blockquote> Users report that this section sometimes doesn't list everything, but I haven't played with this feature enough to understand why that list would not be complete. Second, have you been using the '''about:profiles''' page? If so, the "Root Directory" row should have a button to open that profile's folder. Please back up some files here to a subfolder or somewhere else that Firefox will ignore -- I want to avoid any further overwriting or replacement of these files while you investigate: (1) The '''sessionstore.jsonlz4''' file (if Firefox is not actively running this profile) (2) Contents of the '''sessionstore-backups''' folder, which may include: * 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 the last Firefox session in this profile * upgrade.jsonlz4-''build_id'': the windows and tabs in the Firefox session that was live at the time of your last automatic update (if this profile was running) Sometimes you can tell from the last modification time which one will 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.'' Within the list, tabs should be grouped by: Open Windows, Saved/Closed Tab Groups, Closed Windows. 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. Can you find anything helpful?