Fix Firefox, even Tor version, if it is unable to open magnet links
Firefox may stop out of the blue opening magnet links, and I must say I haven’t found the cause of it, only the solution. Perhaps it’s not always the same cause. Some installation problem, some addon, perhaps if some associations are not well configured by your torrent client, anyway.
Suddenly my Firefox (Tor version) stopped opening magnet links and I tried a lot of things, of course check the magnet associations, registry values, I installed an addon that is supposed to fix content types, even deleted the handlers.json file from inside the default profile of Firefox and reinstalled Tor/Firefox and my Bittorrent client! Nothing worked!
Wow, that was a real frustration!
In my case the problem was solved instantly by adding this value to the preferences of Firefox, you know, the settings page that opens when your write about:config in the address bar. Create a new boolean entrie with the name network.protocol-handler.external.magnet and give it the value true. That’s it. Enjoy!