Do not wait for the error message. Do not trust the broken Microsoft web installer. Download a verified repack of the DirectX End-User Runtimes (June 2010) and store it on your NAS, your game drive, or your IT toolkit USB.
DirectX 12 lives in dxgkrnl.sys and d3d12.dll . The repack writes to completely different file paths. It is impossible to downgrade your core DirectX version this way. directx end user runtimes web installer repack
Would you like a ready-to-use InnoSetup script template, or a batch file to automate the extraction from dxwebsetup.exe ? Do not wait for the error message