Hi RoryMercury, sorry to hear about the inconvenience. Firefox generally stores one previous session, and sometimes Firefox may be opened and closed unexpectedly causing that session to be replaced by a useless one. One workaround is to set Firefox to ALWAYS start up with your previous session tabs and windows. This is set on the Options page, General panel, under "When Firefox starts". Of course, there are also times that a file becomes corrupted or gets deleted, which is hard to work around. ---- You might be able to find older tabs in a backup made by Firefox at your last update. To check on that: Open your current Firefox settings (AKA Firefox profile) folder using either * "3-bar" menu button > "?" button > 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, click the "Open Folder" button. Double-click into the '''sessionstore-backups''' folder. Save all files here to a safe location. 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 Do any seem to be from the right date/time to have some or all of your missing tabs? To preview the contents of a file, you can drag and drop it onto this page, then click Scrounge URLs: https://www.jeffersonscher.com/res/scrounger.html You also can save the page of clickable links as a backup. (That tool is on my site, so please let me know if it doesn't work for you.)