In the same Compatibility tab, check "Disable fullscreen optimizations". Windows’ modern fullscreen handling can conflict with older Direct3D shader calls.
Before fixing the problem, it is essential to understand the terminology. errgfxd3dshader1 work
In plain English: The error means that your computer’s graphics system (DirectX + GPU) failed to compile, locate, or execute a specific shader instruction that the game or application requires. In the same Compatibility tab, check "Disable fullscreen
Many classic games have fan-made patches that replace the Direct3D renderer entirely. Examples include: DxWrapper for older EA games, or cnc-ddraw for Command & Conquer titles. In plain English: The error means that your
Using standard "update" often leaves old files. Instead:
Why this works: Old driver remnants can contain broken shader compilers for Direct3D.
Once you make it work, keep it working: