D3DX11_43.dll is part of the D3DX11 helper library from the DirectX June 2010 release. Games built against it need those older DirectX files, which modern Windows does not include, so a new PC can show this error on an old game even though DirectX 12 is installed.
dxwebsetup.exe). It adds the June 2010 libraries side by side and does not touch DirectX 11 or 12. Restart the PC when done._CommonRedist/DirectX and run DXSETUP.exe there, which installs exactly the libraries that game expects.If the error names a different D3DX11 file, for example D3DX11_42.dll, the same runtime covers it, since the June 2010 package installs the whole D3DX11 set. If the game still fails, reinstall it cleanly, since a damaged game folder can keep failing next to a healthy runtime.
I have DirectX 12, why is a DirectX file missing? The version number only covers the core components. D3DX11 is an optional helper library from the old DirectX SDK, and Windows Update does not provide it. The DirectX End-User Runtime is what adds it.
Is the DirectX End-User Runtime safe? Yes, it is Microsoft's own installer, still offered on the Microsoft Download Center. It only adds the older libraries and changes nothing about DirectX 11 or 12.