%APPDATA%\Mozilla\Firefox\Profiles

Hi, I have a guess about what happened and how to fix it. Question: Did Firefox start up with an early Primary Password prompt, and you canceled it? On first run, Firefox 127 runs some code that doesn't work normally if the Primary Password is canceled, and this causes session loss and broken display. Next steps: '''(1) Open your profile folder...''' ''If Firefox is still running:'' 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" button. This should launch Windows' File Explorer listing the contents of your current profile folder. ''If Firefox is closed:'' Type or paste the following into the Windows Run dialog or the system search box and press Enter to launch Windows Explorer: %APPDATA%\Mozilla\Firefox\Profiles In that folder, do you see a semi-randomly-named folder? If so, click into it. If you find multiple such folders, find the one that was most recently updated. '''(2) Back up 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. '''(3) Substitute session history files''' The two files most likely to contain your lost tabs are: * previous.jsonlz4: the windows and tabs in your last Firefox session as of the time Firefox failed to restore them, assuming you haven't already started a new session * upgrade.jsonlz4-20240606181944 (this number may vary, but it should start with 20240606): the windows and tabs in the Firefox session that was live at the time of your last update Choose one to try and -- with Firefox closed: (A) Right-click recovery.jsonlz4 and rename to recoveryOLD.jsonlz4 (B) Single-click the file to select it (C) Copy the file using Ctrl+C (D) Paste the file using Ctrl+V (the new file is named something along the lines of "previous - Copy.jsonlz4") (E) Right-click the new file and rename to recovery.jsonlz4 Before restarting Firefox, click up a level in the address bar to the main level of the profile folder. If you find a sessionstore.jsonlz4 file, rename it to sessionstoreOLD.jsonlz4 to hide it from Firefox. At the next startup, Firefox should automatically use or let you restore the substitute recovery.jsonlz4. Success? ---- '''''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.

Hi I wasn't able to restore my tabs, but was able to save a list using your tool, so thanks a lot mate.

Do you have a Primary Password set?