Windows 10 SDK Preview Build 18950 now available for developers

A new Windows 10 SDK preview has been pushed out by Microsoft for developers to try out. The new SDK is build 18950, which matches the latest version of Windows 10 to ship to Fast ring Insiders. Microsoft also released ISO files of build 18950 earlier today.

Here's a look at what's available with Windows 10 SDK Preview Build 18950:

Tools Updates

  • Now detects the Unicode byte order mark (BOM) in .mc files. [If the] .mc file starts with a UTF-8 BOM, it will be read as a UTF-8 file. Otherwise, if it starts with a UTF-16LE BOM, it will be read as a UTF-16LE file. If the -u parameter was specified, it will be read as a UTF-16LE file. Otherwise, it will be read using the current code page (CP_ACP).
  • Now avoids one-definition-rule (ODR) problems in MC-generated C/C++ ETW helpers caused by conflicting configuration macros (e.g. when two .cpp files with conflicting definitions of MCGEN_EVENTWRITETRANSFER are linked into the same binary, the MC-generated ETW helpers will now respect the definition of MCGEN_EVENTWRITETRANSFER in each .cpp file instead of arbitrarily picking one or the other).

Breaking Changes

  • In this release irprops.lib has been removed from the Windows SDK. Apps that were linking against irprops.lib can switch to bthprops.lib as a drop-in replacement.
  • In addition to these updates and changes, there are several API updates, additions, and removals that you should know about. You can see all the details in the full release notes from Microsoft.

In addition to the updates and changes listed above, there are a number of API updates, additions, and removals to be aware of. For the full list, you can check out Microsoft's complete release notes.

As with other SDK releases, you can install 18950 with Visual Studio 2017 alongside previous SDKs. Developers can download Windows 10 SDK Preview Build 18950 from the Insider downloads page now.

Sean Endicott
News Writer and apps editor

Sean Endicott brings nearly a decade of experience covering Microsoft and Windows news to Windows Central. He joined our team in 2017 as an app reviewer and now heads up our day-to-day news coverage. If you have a news tip or an app to review, hit him up at