I had some virus on my computer and it messed up some system files. I had a lot of dll errors on system startup. Anyway, after reinstalling windows 7 x64 all of those errors disappeared. I’ve scanned my computer multiple times with various antivirus utilities and it looks like it is clean from infections. However, when I tried to run Assassin’s Creed 4 Black Flag I was getting d3dcompiler_43.dll is missing error. I found that this error is common for Assassin’s Creed 4 and other games and there is a quite simple fix for it.
D3dcompiler_43.dll is a dynamic library used by DirectX. If you have error saying that d3dcompiler_43.dll is missing it means that the program cannot locate that file or it is damaged. The best and easiest way to fix it is to download and installs the missing d3dcompiler_43.dll file from here: http://fix4dll.com/d3dcompiler_43_dll.
This should fix your d3dcompiler_43.dll is missing error in Assassin’s Creed 4. Enjoy playing!