Sorry to hear about this problem. Here are two things you could try: '''(A) Database Maintenance''' The Troubleshooting Information page has a "Verify Integrity" button to do a little light maintenance on the Places database (where bookmarks and history are stored). You can open that using either * "3-bar" menu button > "?" Help > Troubleshooting Information * (menu bar) Help > Troubleshooting Information * type or paste about:support in the address bar and press Enter Then scroll way down or use Find to search for ''Integrity'' in the Places Database section. At first, nothing will seem to happen, but then several seconds after clicking the button Firefox should report some diagnostic results below it. Please copy/paste the results somewhere safe, then quit/restart Firefox to see whether it helped. Can you restore a backup? '''(B) Clean/Convert Backup File''' Sometimes a backup file may have structural corruption from an older version that prevents restoring it to a newer version. You can try cleaning out issues in the backup file, or converting it to an importable HTML file. (1) Open your bookmarkbackups folder using these steps: Either: * "3-bar" menu button > "?" Help > 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, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer. Double-click into the '''bookmarkbackups''' folder. Here you should find files with names like: bookmarks-2018-10-14_6133_''gibberish''==.jsonlz4 (2) Leaving that window open, switch over to Firefox and open this page in a Firefox tab: https://www.jeffersonscher.com/ffu/bookbackreader.html (3) Resize/reposition the Windows Explorer window so you can drag-and-drop one of your backup files onto the white box in the page. A script in the page should decompress the file and extract the data. Then: (4) Try the "Check/Repair" button and if the script reports that it found and fixed issues, save the JSON format file to a convenient location. (5) Also save the HTML export option. ''If the page starts demanding a lot of resources, you can close the tab now.'' '''If you created a JSON file:''' Try to restore it using the "Choose File..." item at the bottom of the Restore menu described in: [[Restore bookmarks from backup or move them to another computer]]. '''If that didn't work:''' Use Firefox's Import feature to pull in the HTML file: [[Import Bookmarks from an HTML file]]. After importing, Firefox may place the entire contents in a "Imported Bookmarks" folder on the Bookmarks menu. In that case, you can manually reorganize using the panes of the Library window. Success?