This happens even when the same programs or executable files have run on the same or other 64-bit Windows 11/10 PCs. The program or feature cannot start or run due to incompatibility with 64-bit ...

I have the pleasure of supporting an ancient 16 bit program for a client. It worked fine on their old server running Windows Server 2003 (32 bit) but will not work now that a new 2008 R2 server ...

Some DOS programs will not work in any current version of Windows. Generally, these are utilities that work close to the hardware, such as defraggers and diagnostic tools.