Cannot Launch League of Legends Game with Unknown DirectX Error

When I try to start the game, it shows me the following error. what can I do?

enter image description here


This is a known error with the new patch (7.9).

One fix that seems to be working for a majority of people is the config reset

Try this:

  1. Go to C:\Riot Games\League of Legends\Config

  2. Delete game.cfg file

    enter image description here

  3. Launch the game, does same issue occur?

Since this is a rather common issue Riot has also started a support thread in the official forums.