How to fix The program can’t start because d3dx9_42.dll is missing from your computer

If you’re getting the following error “The program can’t start because d3dx9_42.dll is missing from your computer. Try reinstalling the program to fix this problem.” when loading a game the fix might be as simple as a download.

Try downloading the DirectX End-User Runtime Web Installer from the Microsoft site here.

I was getting this error when trying to load ArcheAge and installing the DirectX End-User Runtime worked for me.