My browser builds (part 2) in Windows XP Posted 19 hours ago 4 hours ago, DanR20 said: Open the addon with 7-zip or a similar program and on the root there’s a file manifest.json. If you’re using 7-zip right click edit to open it and nine lines down you’ll see: "strict_min_version": "68.0" Just change it to this: "strict_min_version": "52.0" Save and close and it should install. I already had the previous version on there so all that was needed was to swap the old one with the new one. It works, thank you so much! The only thing which doesn't seem to work in Firefox 52.9 ESR is the snapshot feature, which does nothing. Personally I can live without that! It sometimes doesn't load when you first load a YouTube video, but the old version I was using used to do that as well. Refreshing the page makes it come good and it's then OK on subsequent videos. Off-topic here of course, but I hope this will help others. Cheers, Dave.