DLL not a valid win32 application?

Question

Cocos2d

After cleaning and rebuilding the sln file, it began to knock out an error, why and how to solve it?
I tried StartUp Projects, they all give a similar error.
Windows 10, VS Community 2019
Here did according to this answer
https://stackoverflow.com/questions/16422883/error...

Answer 1

Startup project must be an executable exe file, not a dll.