Looks like you are on version 52. Is that where you started ? Profiles are not backwards compatible from 57+ so you will have to see if have 2 Profiles and can merge the info. https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data if find 2 Profiles or more : https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile Always have a copy of Bookmarks saved this way : https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer if do then can save and copy over top with newer ones. So figure above and below out and if need help merging Profiles if it is still possible please come back and ask. It was probably not wise to go up with XP. You should be running a Secure and Supported Browser : 52.5.0 ESR is where most XP users are. It will continue to get security updates until May 2018, and you can download and install it from this page: https://www.mozilla.org/en-US/firefox/organizations/all/ <b>Note : Legacy Extensions will be deleted or removed in any version update after May 2018</b>. You should make a backup of your Profile before going back and just because: https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles Please let us know if this solved your issue or if need further assistance.