Firing Custom Scheme URL Results in An Error Saying "Unknown protocol 'tg'."

Launching a URL in browser redirects you to a URL with custom scheme like:


This usually causes to fire up Telegram and open up the related group/channel/whatever.

In my case, it fires up Telegram (which is always running on my machine). I can see it does because the icon bounces next to my cursor. However, it finalizes with an error saying:

Unable to create io-slave. klauncher said: Unknown protocol 'tg'.

Why does it not launch?


  • System: Manjaro KDE 20.2
  • Desktop: Plasmashell 5.20.4
  • Browser: Opera 72.0.3815.400

Oddly, the issue is not present in Firefox.

So it’s easy to solve

  1. Open the folder ~/.local/share/applications
  2. find some files about telegram desktop, like example, my is userapp-Telegram Desktop-FXJ6T0.desktop
  3. Add the line at the end of file MimeType=application/x-xdg-protocol-tg;x-scheme-handler/tg;
  4. Reload your browser (maybe do not need…)
  5. Enjoy!
1 Like

This topic was automatically closed 15 days after the last reply. New replies are no longer allowed.