If you use two or more monitors, the game sometimes tries to initialize on a non-existent or wrong screen.
If the game is trying to use an unsupported display mode, you can manually reset it: serious sam 3 cannot set display mode
: Forcing the game to switch between DirectX 9, DirectX 11, or Vulkan without the right software runtimes installed causes an instant crash. Core Solutions to Fix the Crash If you use two or more monitors, the
The game engine (Serious Engine 3.5) fails to initialize a compatible DirectX or OpenGL display mode due to: It is simply a handshake problem between old
The "Cannot set display mode" error is not a sign that your PC is broken or that Serious Sam 3 is unplayable. It is simply a handshake problem between old code and new hardware. By forcing a standard resolution, clearing corrupted configs, or adjusting GPU settings, you can almost always get back to mowing down hordes of headless bombers in no time.
The "cannot set display mode" error in Serious Sam 3: BFE typically happens when the game tries to launch at a resolution or refresh rate your monitor doesn't support, or when essential DirectX components are missing
The Serious Engine 3.5 has a known feud with Windows 10/11’s DPI virtualization and full-screen optimizations.