Current Firefox releases keep 15 JSON backups (about:config -> browser.bookmarks.max_backups = 15). How many JSON backups do you see in the Library? You can check for problems with the <b>places.sqlite</b> database file in the Firefox profile folder. *http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox *https://support.mozilla.org/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file *Places Maintenance: https://addons.mozilla.org/firefox/addon/places-maintenance/