> browser_specific_settings Yeah I noticed that's the answer when I googled the error just now. Not sure why I didn't see it or it somehow didn't work at that

> browser_specific_settings Yeah I noticed that's the answer when I googled the error just now. Not sure why I didn't see it or it somehow didn't work at that time, the information should have been available (I encountered the problem late last year). It's certainly misleading that the error message links to a bug, at least giving the impression that it is a bug, rather than a guide. That said, IMO the underlying issue that Firefox doesn't allow you to just install an extension from a source directory like Chrome/Chromium does is much worse.