Fatal error: "No Target Architecture" in Visual Studio

Question

Use #include <windows.h> instead of #include <windef.h>.

From the windows.h wikipedia page:

There are a number of child header files that are automatically included with windows.h. Many of these files cannot simply be included by themselves (they are not self-contained), because of dependencies.

windef.h is one of the files automatically included with windows.h.

Another cause of this can be including a header that depends on windows.h, before including windows.h.

In my case I included xinput.h before windows.h and got this error. Swapping the order solved the problem.

Solve it by placing the following include files and definition first:

#define WIN32_LEAN_AND_MEAN      // Exclude rarely-used stuff from Windows headers

#include <windows.h>

If you are using Resharper make sure it does not add the wrong header for you, very common cases with ReSharper are:

• #include <consoleapi2.h
  
• #include <apiquery2.h>
• #include <fileapi.h>

UPDATE:
Another suggestion is to check if you are including a "partial Windows.h", what I mean is that if you include for example winbase.h or minwindef.h you may end up with that error, add "the big" Windows.h instead. There are also some less obvious cases that I went through, the most notable was when I only included synchapi.h, the docs clearly state that is the header to be included for some functions like AcquireSRWLockShared but it triggered the No target architecture, the fix was to remove the synchapi.h and include "the big" Windows.h.

The Windows.h is huge, it defines macros(many of them remove the No target arch error) and includes many other headers. In summary, always check if you are including some header that could be replaced by Windows.h because it is not unusual to include a header that relies on some constants that are defined by Windows.h, so if you fail to include this header your compilation may fail.

_WIN32 identifier is not defined.

use #include <SDKDDKVer.h>

MSVS generated projects wrap this include by generating a local "targetver.h"which is included by "stdafx.h" that is comiled into a precompiled-header through "stdafx.cpp".

EDIT : do you have a /D "WIN32" on your commandline ?

It would seem that _AMD64_ is not defined, since I can't imagine you are compiling for Itanium (_IA64_).

At the beginning of the file you are compiling, before any include, try to put ONE of these lines

#define _X86_
#define _AMD64_
#define _ARM_

Choose the appropriate, only one, depending on your architecture.