Here’s a proper technical write-up for the issue — suitable for a knowledge base, bug report, or support forum.
The "Fatal Error: Cannot set display mode" in Serious Sam 3: BFE serious sam 3 cannot set display mode
If the quick checklist doesn’t help, proceed with the full steps below. "Serious Sam 3: Cannot set display mode" Here’s
Documents\Serious Sam 3\Scripts\ and open PersistSam3.ini using Notepad.gfx_pixRefreshRate
Set this to 60 (a standard safe value).gfx_pixHeight
and
gfx_pixWidth
Set these to your monitor's native resolution (e.g., Width: 1920, Height: 1080).