Windows 10 build 17035 SDK preview now available for developers

A new preview build of the Windows 10 SDK is now available for developers, bringing along a handful of changes and additions for Windows 10 build 17035. This is the second Redstone 4 SDK build to hit developers, following the launch of the 17025 SDK preview earlier in November.

Here's a look at the short list of what's new:

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

A full list of API additions since build 126299 can also be found in Microsoft's full release notes. Developers can download the SDK preview release from Microsoft now.

Though the list of SDK changes may be short, Microsoft has a bit more in store for Windows Server users. The company also launched Windows Server Insider Preview Build 17035 today, bringing a couple of changes. Here's a look:

  • Storage Spaces Direct (S2D) is enabled. Storage Spaces Direct is the foundation of our hyper-converged solution and we're continuing to evolve it. In this preview build we not only brought it back, but we're adding some new and important updates to it – such as support for Data Deduplication, a commonly requested feature for Storage Spaces Direct and ReFS. Starting with this build, ata Deduplication will reduce the data footprint by up to 50%.
  • Developers can now use localhost or loopback ( to access services running in containers on the host.

This build also includes some improvements to Project Honolulu, Microsoft's browser-based platform for managing Windows Server troubleshooting, configuration, and maintenance.

Dan Thorp-Lancaster

Dan Thorp-Lancaster is the former Editor-in-Chief of Windows Central. He began working with Windows Central, Android Central, and iMore as a news writer in 2014 and is obsessed with tech of all sorts. You can follow Dan on Twitter @DthorpL and Instagram @heyitsdtl