An Unknown DirectX Error Has Occurred

"An Unknown DirectX Error has Occurred and League of Legends cannot start. Please make sure your video card is using the latest video drivers from the manufacturer."

This error pops up when I get to the loading screen after champ select on both Live and PBE servers. I've updated my video driver and am already on DirectX 12 so idk what's wrong. I think it might be due to my new monitor because the game worked fine with my old one, which was about a week ago, but I'm not sure. Please help.[zombie-nunu-tears]