Firefox doesn’t know how to open this address, because one of the following protocols (fb-messenger) isn’t associated with any program or is not allowed in this context.

Hi soulgoneglass, I haven't personally encountered a link that starts with fb-messenger: instead of https: but it sounds like you found one. Do you know whether the link is supposed to open FB Messenger in the browser, or a separate FB Messenger app? Or maybe it's only intended to work on mobile and not on Windows?