I'm trying to run League of Legends on a Windows 10 x64 computer. I can launch the main screen, but when I try to start an actual game, it fails with a message stating:
System Error
The program can't start because d3dx9_39.dll is missing from your computer. Try reinstalling the program to fix this problem.
I've tried reinstalling both League of Legends and DirectX9 (from the DirectX End-User Runtime Web Installer), but both of them say DirectX9 is already installed and won't change a thing.
I don't find any option to uninstall DirectX from the Control Panel.
Funny thing is - I see a d3dx9_39.dll file in both C:\Windows\System32\d3dx9_39.dll and C:\Windows\SysWOW64\d3dx9_39.dll.
How can I reinstall the missing DirectX9 components?
1 Answer
The solution to this was simple, albeit ugly - delete/rename the problematic dlls.
I've renamed both d3dx9_39.dll files (in both C:\Windows\System32\d3dx9_39.dll and C:\Windows\SysWOW64\d3dx9_39.dll) to something like __d3dx9_39.dll, and re-ran the DirectX9 Runtime Web Installer. Since there's now no file called d3dx9_39.dll, the Web Installer will happily download them from the internet and install them from scratch.
Deleting the files (instead of renaming them) works the same, but I wanted to keep copies around just in case.
