Fixed: League of Legends d3dx9_39.dll error
I just did a clean install of Windows 11 and League of Legends didn't work. I could log in and ready up, but when the match started I got the error "The program can't start because d3dx9_39.dll is missing from your computer. Try reinstalling the program to fix this problem."
This is an EMERGENCY!
The fix is/was to install the DirectX End-User Runtime Web Installer from Microsoft. It's a tiny download and installs fast. That did the trick, and I was able to get this fixed in time to win the match.