Is there any other data missing, such as bookmarks, add-ons, previous session tabs, or just logins? Did Firefox perform a Refresh during your update? The telltale sign is a folder on your desktop named Old Firefox Data which could come in handy for recovering old data. And just to confirm, you have not tried to use the Windows System Restore feature, and please, please don't. ''Assuming just logins and no Old Firefox Data:'' Could you check whether Windows made any backups of a particular data file in your profile? Here's how: 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. This should launch a new window listing various files and folders in Windows Explorer. Find a file named '''logins.json''', right-click it, choose Properties, then activate the Previous Versions tab. Here Windows will list any backup copies of this file available in previous restore points. If you see any, use the Copy... button to copy them out to a separate but convenient location such as your Documents folder (you may need to rename each one you restore to avoid name conflicts, e.g., for April 23rd logins-423.json). Did you find any candidates that you want to try out?