Error LNK2001 Unresolved Symbol on DLL Entry Point

Symptoms

The error shown below occurs when linking a DLL.

entry-varies.obj : error LNK2001: unresolved external symbol DllMain@12
fatal error LNK1120: 1 unresolved externals

Your DLL entry point DllMain calling convention, parameters, or return type do not conform to the Win32 specification for DllMain:

BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved);

Use one of the alternative resolutions listed below.

Modify your source code to change your DllMain callback function so that the parameters and return type match the Win32 documentation.

Insert extern "C" in front of your DllMain function definition. For example:

extern "C"
BOOL WINAPI myDllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)

Rename your entry point function DllMain. Since this name is the default, you can delete your link option /ENTRYPOINT.

Updated: 22 Oct 2018