Today, we released a new Windows 10 Preview Build of the SDK to be used in conjunction with Windows 10 Insider Preview (Build 17115 or greater). The Preview SDK Build 17115 contains bug fixes and under development changes to the API surface area.The Preview SDK can be downloaded from developer section on Windows Insider.

For feedback and updates to the known issues, please see the developer forum. For new developer feature requests, head over to our Windows Platform UserVoice.

Things to note:

  • This build works in conjunction with previously released SDKs and Visual Studio 2017. You can install this SDK and still also continue to submit your apps that target Windows 10 Creators build or earlier to the store.
  • The Windows SDK will now formally only be supported by Visual Studio 2017 and greater. You can download the Visual Studio 2017 here.

Known Issues

What’s New:

  • C++/WinRT Now Available: The C++/WinRT headers and cppwinrt compiler (cppwinrt.exe) are now included in the Windows SDK. The compiler comes in handy if you need to consume a third-party WinRT component or if you need to author your own WinRT components with C++/WinRT. The easiest way to get working with it after installing the Windows Insider Preview SDK is to start the Visual Studio Developer Command Prompt and run the compiler in that environment. Authoring support is currently experimental and subject to change. Stay tuned as we will publish more detailed instructions on how to use the compiler in the coming week. The ModernCPP blog has a deeper dive into the CppWinRT compiler. Please give us feedback by creating an issue at:

Breaking Changes

  • New MIDL key words.

As a part of the “modernizing IDL” effort, several new keywords are added to the midlrt tool. These new keywords will cause build breaks if they are encountered in IDL files.

The new keywords are:

  • event
  • set
  • get
  • partial
  • unsealed
  • overridable
  • protected
  • importwinmd

If any of these keywords is used as an identifier, it will generate a build failure indicating a syntax error.

The error will be similar to:

>d:\os\src\onecore\com\combase\unittest\astatestservers\testserver6\idl\remreleasetest.idl(12) : error MIDL2025 : [msg]syntax error [context]: expecting a declarator or * near “)”

To fix this, modify the identifier in error to an “@” prefix in front of the identifier. That will cause MIDL to treat the offending element as an identifier instead of a keyword.

API Updates and Additions

When targeting new APIs, consider writing your app to be adaptive in order to run correctly on the widest number of Windows 10 devices. Please see Dynamically detecting features with API contracts (10 by 10) for more information.

The following APIs have been added to the platform since the release of 16299...

Read more: Windows 10 SDK Preview Build 17115 now available - Windows Developer Blog