hello steve, all your personal data and customizations will still be there in the updated version. however it is never a bad idea to create a backup once in a while: [[Back up and restore information in Firefox profiles]]

The tabs that are currently open and App (pinned) tabs and tab groups are stored in the sessionstore.js file in the Firefox profile folder, so you can backup this file and restore it to get the tabs from that session. *http://kb.mozillazine.org/sessionstore.js *http://kb.mozillazine.org/Session_Restore *https://support.mozilla.org/kb/restore-previous-session See also: *http://kb.mozillazine.org/Backing_up_and_restoring_bookmarks_-_Firefox *https://support.mozilla.org/kb/Recovering+important+data+from+an+old+profile