If you use Sync then best is to disconnect Sync temporarily during troubleshooting. You can check for problems with the <b>places.sqlite</b> database (bookmarks and history) in the Firefox profile folder. *use "Verify Integrity" on the "Help -> Troubleshooting Information" (about:support) page<br>close and restart Firefox in case errors are reported and retry See also: *http://kb.mozillazine.org/Locked_or_damaged_places.sqlite *https://support.mozilla.org/en-US/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file If "Verify Integrity" on the "Help -> Troubleshooting Information" (about:support) page cannot repair places.sqlite then remove all places.sqlite files in the Firefox profile folder. Firefox will rebuild places.sqlite and restore the bookmarks from a recent JSON backup in the bookmarkbackups folder. *keep a backup copy of places.sqlite in case a new places.sqlite database has to be created *http://kb.mozillazine.org/Unable_to_process_the_backup_file_-_Firefox You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the <b>about:profiles</b> page. *Help -> Troubleshooting Information -> Profile Directory:<br>Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder *http://kb.mozillazine.org/Profile_folder_-_Firefox