“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

If you encounter this error when you click green arrow button to run the application, but still want to run the app in 64 bit. You can do this in VS 2013, 2015, 2017, and 2019

Go to: Tools > Options > Projects and Solutions > Web Projects > Use the 64 bit version of IIS Express