Hi, the extension uses the new webextensions api which will eventually completely replace legacy extension. Unfortunately it doesn’t work on versions before 57, when webextensions were introduced.

Thank you for your feedback. I’ve implemented your first suggestion in the latest release. When it comes to the second one I’m skeptical. I do most of my bookmark related stuff in the bookmarks sidebar. Having the errors in the sidebar, I can quickly review them without window switching/rearranging and now I can keep an eye on the progress while opening other tabs - for example to review an error. I consider reducing the font-size of the list though. Displaying bookmarks in the sidebar should be possible on every screen, shouldn’t it? I think I don’t expect too much when I’m expecting people to resize their sidebar. Maybe a misconception ;) Maybe there are even screens where the sidebar can’t get wide enough but how does the bookmark sidebar work on that screens? Well, I will keep that in mind...

I see... thanks again! Actually I was waiting for a replacement for FavIcon Reloader, but at the moment it does not seem to be possible to port its functionality to the new addon-ecosystem. I think that's why the developer could not update it for newer versions of firefox and it is the reason why I came up with this workaround. With 10.000 bookmarks you could always backup/restore your favicons.sqlite, favicons.sqlite-shm and favicons.sqlite-wal files in your profile folder or let this extension run for two hours and turn of the heating instead ;) Maybe, on the other hand side, you can reduce your number of bookmarks by finding many dead links...