Maybe you have been modifying your Firefox History, & or are modifying the files you are trying to import. * a previous thread of yours ''Simple guide for using SQLite Manager with Mac Firefox browsing history'' [/questions/953912] #Create a new additional Firefox profile. Ensure it has only the default bookmarks, and a clean History. <br/>[[Use the Profile Manager to create and remove Firefox profiles]] #Try importing into that, to reassure yourself Firefox normally works with imports. <br/>[[Import Bookmarks and personal data from another browser]] You may find this add-on useful * https://addons.mozilla.org/en-US/firefox/addon/places-maintenance/ The addon may be able to fix problems, and may be able to give a diagnostic report.