''<p>dougjp [[#question-1355406|said]]</p>'' <blockquote>Two questions re: the forced update from 78.15 to 91. 1: Will all bookmarks, and all other settings be retained? Is there a form of recommended backup in case of problems (I currently use MozBackup, still) </blockquote> Your profile will be migrated and bookmarks should be fine. Of course it doesn't hurt to make backups! Some of your settings might not work any more or might work differently due to changes between Firefox 78 and Firefox 91, but there are so many changes in a year that it's difficult to think of specific examples. <blockquote>2: Will the "Bookmark Tab Here" add-on work with 91? I need a user friendly bookmarking system, which was the reason I stayed with ESR in the first place. </blockquote> I don't see any problems in the reviews during the past year, so it appears the author has been keeping up with changes in Firefox: https://addons.mozilla.org/firefox/addon/bookmark-tab-here/reviews/