[c++] Visual Studio 2017 errors on standard headers

I just upgraded to Visual Studio 2017 Community Edition and I have trouble loading standard header files. I get 507 errors from various header files. Here are some snippets:

Some of the errors:

Severity    Code    Description Project File    Line    Suppression State
Error (active)  E1696   cannot open source file "errno.h"   RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cerrno  7   
Error (active)  E1696   cannot open source file "float.h"   RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cfloat  7   
Error (active)  E0282   the global scope has no "acosf" RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cmath   629 
Error (active)  E0282   the global scope has no "asinf" RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cmath   629 
Error (active)  E0282   the global scope has no "atanf" RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cmath   630 
Error (active)  E0282   the global scope has no "atan2f"    RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cmath   630 
Error (active)  E0282   the global scope has no "ceilf" RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cmath   630 
Error (active)  E0282   the global scope has no "cosf"  RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cmath   631 
Error (active)  E0282   the global scope has no "coshf" RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cmath   631 
Error (active)  E0282   the global scope has no "swprintf"  RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  21  
Error (active)  E0282   the global scope has no "swscanf"   RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  21  
Error (active)  E0282   the global scope has no "ungetwc"   RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  21  
Error (active)  E0282   the global scope has no "vfwprintf" RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  22  
Error (active)  E0282   the global scope has no "vswprintf" RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  22  
Error (active)  E0282   the global scope has no "vwprintf"  RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  22  
Error (active)  E0282   the global scope has no "wcrtomb"   RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  23  
Error (active)  E0282   the global scope has no "wprintf"   RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  23  
Error (active)  E0282   the global scope has no "wscanf"    RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  23  
Error (active)  E0282   the global scope has no "wcsrtombs" RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  24  
Error (active)  E0282   the global scope has no "wcstol"    RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  24  
Error (active)  E0282   the global scope has no "wcscat"    RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  24  
Error (active)  E0282   the global scope has no "wcschr"    RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  25  
Error (active)  E0282   the global scope has no "wcscmp"    RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  25  
Error (active)  E0282   the global scope has no "wcscoll"   RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  25  
Error (active)  E0282   the global scope has no "wcscpy"    RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  26  
Error (active)  E0282   the global scope has no "wcscspn"   RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  26  
Error (active)  E0282   the global scope has no "wcslen"    RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  26  
Error (active)  E0282   the global scope has no "wcsncat"   RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  27  
Error (active)  E0282   the global scope has no "wcsncmp"   RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  27  
Error (active)  E0282   the global scope has no "wcsncpy"   RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  27  
Error (active)  E0282   the global scope has no "wcspbrk"   RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\cwchar  28  
Error (active)  E0282   the global scope has no "wcsrchr"   RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools
Error (active)  E0260   explicit type is missing ('int' assumed)    RPGWorld    c:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\include\xtgmath.h   212 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\Graphics\Glsl.inl    40  
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\Graphics\Texture.hpp 159 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\Graphics\VertexArray.hpp 64  
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\Graphics\VertexArray.hpp 72  
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\Graphics\VertexArray.hpp 88  
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\Graphics\VertexArray.hpp 104 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\Graphics\VertexArray.hpp 129 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\System\String.hpp    58  
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\System\String.hpp    332 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\System\String.hpp    345 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\System\String.hpp    365 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\System\String.hpp    387 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\System\String.hpp    387 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\System\String.hpp    399 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\System\String.hpp    413 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\System\String.hpp    413 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\System\String.hpp    427 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\System\String.hpp    427 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\System\String.hpp    456 
Error (active)  E0757   variable "size_t" is not a type name    RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\packages\sfml-system.2.4.0.0\build\native\include\SFML\System\String.hpp    456 
Error (active)  E0020   identifier "rand" is undefined  RPGWorld    c:\Users\Fazil\Documents\Visual Studio 2017\Projects\Local\RPGWorld\RPGWorld\Blocks.cpp 23  
Error   C1083   Cannot open include file: 'corecrt.h': No such file or directory    RPGWorld    c:\program files (x86)\microsoft visual studio\2017\community\vc\tools\msvc\14.10.25017\include\crtdefs.h   10  
Error   C1083   Cannot open include file: 'corecrt.h': No such file or directory    RPGWorld    c:\program files (x86)\microsoft visual studio\2017\community\vc\tools\msvc\14.10.25017\include\crtdefs.h   10  
Error   C1083   Cannot open include file: 'corecrt.h': No such file or directory    RPGWorld    c:\program files (x86)\microsoft visual studio\2017\community\vc\tools\msvc\14.10.25017\include\crtdefs.h   10  
Error   C1083   Cannot open include file: 'corecrt.h': No such file or directory    RPGWorld    c:\program files (x86)\microsoft visual studio\2017\community\vc\tools\msvc\14.10.25017\include\crtdefs.h   10  
Error   C1083   Cannot open include file: 'corecrt.h': No such file or directory    RPGWorld    c:\program files (x86)\microsoft visual studio\2017\community\vc\tools\msvc\14.10.25017\include\crtdefs.h   10  
Error   C1083   Cannot open include file: 'corecrt.h': No such file or directory    RPGWorld    c:\program files (x86)\microsoft visual studio\2017\community\vc\tools\msvc\14.10.25017\include\crtdefs.h   10  
Error   C1083   Cannot open include file: 'corecrt.h': No such file or directory    RPGWorld    c:\program files (x86)\microsoft visual studio\2017\community\vc\tools\msvc\14.10.25017\include\crtdefs.h   10  
Error   C1083   Cannot open include file: 'corecrt.h': No such file or directory    RPGWorld    c:\program files (x86)\microsoft visual studio\2017\community\vc\tools\msvc\14.10.25017\include\crtdefs.h   10  

I never had this issue with Visual Studio 2015 Community Edition. Am I missing some component from the Installer? Any help would be appreciated. Thank you!

This problem may also happen if you have a unit test project that has a different C++ version than the project you want to test.

Example:

• EXE with C++ 17 enabled explicitly
• Unit Test with C++ version set to "Default"

Solution: change the Unit Test to C++17 as well.

If the problem is not solved by above answer, check whether the Windows SDK version is 10.0.15063.0.

Project -> Properties -> General -> Windows SDK Version -> select 10.0.15063.0

After this rebuild the solution.  

I upgraded VS2017 from version 15.2 to 15.8. With version 15.8 here's what happened:

Project -> Properties -> General -> Windows SDK Version -> select 10.0.15063.0 no longer worked for me! I had to change it to 10.0.17134.0 and then everything built again. After the upgrade and without making this change, I was getting the same header file errors.

I would have submitted this as a comment on one of the other answers but I don't have enough reputation yet.

If anyone's still stuck on this, the easiest solution I found was to "Retarget Solution". In my case, the project was built of SDK 8.1, upgrading to VS2017 brought with it SDK 10.0.xxx.

To retarget solution: Project->Retarget Solution->"Select whichever SDK you have installed"->OK

From there on you can simply build/debug your solution. Hope it helps