“An attempt was made to load a program with an incorrect format” even when the platforms are the same

Question

I\'m calling functions from a 32-bit unmanaged DLL on a 64-bit system. What I get is:

BadImageFormatException: An attempt was made to load a program w

Answer 1

In my case, I was running tests through MSTest and found out that I was deploying both a 32-bit and 64-bit DLL to the test directory. The program was favoring the 64-bit DLL and causing it to fail.

TL;DR Make sure you only deploy 32-bit DLLs to tests.