Windows 10 SDK Preview build 17666 is now available to download

Microsoft has released a new Windows 10 Preview Build of the SDK that can be used in conjunction with Windows 10 (Redstone 5) Build 17666 or greater. The Preview SDK Build 17666 contains bug fixes and under development changes to the API surface area.

First up, the known issues:

Installation on an operating system that is not a Windows 10 Insider Preview build is not supported and may fail.

The contract Windows.System.SystemManagementContract is not included in this release. In order to access the following APIs, please use a previous Windows IoT extension SDK with your project.

This bug will be fixed in a future preview build of the SDK.

The following APIs are affected by this bug:

namespace Windows.Services.Cortana {
  public sealed class CortanaSettings     
namespace Windows.System {
  public enum AutoUpdateTimeZoneStatus
  public static class DateTimeSettings
  public enum PowerState
  public static class ProcessLauncher
  public sealed class ProcessLauncherOptions
  public sealed class ProcessLauncherResult
  public enum ShutdownKind
  public static class ShutdownManager
  public struct SystemManagementContract
  public static class TimeZoneSettings

API Spot Light:

Check out LauncherOptions.GroupingPreference.

namespace Windows.System {
  public sealed class FolderLauncherOptions : ILauncherViewOptions {
    ViewGrouping GroupingPreference { get; set; }
  public sealed class LauncherOptions : ILauncherViewOptions {
    ViewGrouping GroupingPreference { get; set; }

This release contains the new LauncherOptions.GroupingPreference property to assist your app in tailoring its behavior for Sets. Watch the presentation here.

... and What’s New:


We’ve made some important changes to the C/C++ ETW code generation of mc.exe (Message Compiler):

The “-mof” parameter is deprecated. This parameter instructs MC.exe to generate ETW code that is compatible with Windows XP and earlier. Support for the “-mof” parameter will be removed in a future version of mc.exe.

As long as the “-mof” parameter is not used, the generated C/C++ header is now compatible with both kernel-mode and user-mode, regardless of whether “-km” or “-um” was specified on the command line. The header will use the _ETW_KM_ macro to automatically determine whether it is being compiled for kernel-mode or user-mode and will call the appropriate ETW APIs for each mode.

  • The only remaining difference between “-km” and “-um” is that the EventWrite[EventName] macros generated with “-km” have an Activity ID parameter while the EventWrite[EventName] macros generated with “-um” do not have an Activity ID parameter.

The EventWrite[EventName] macros now default to calling EventWriteTransfer (user mode) or EtwWriteTransfer (kernel mode). Previously, the EventWrite[EventName] macros defaulted to calling EventWrite (user mode) or EtwWrite (kernel mode).

  • The generated header now supports several customization macros. For example, you can set the MCGEN_EVENTWRITETRANSFER macro if you need the generated macros to call something other than EventWriteTransfer.
  • The manifest supports new attributes.
    • Event “name”: non-localized event name.
    • Event “attributes”: additional key-value metadata for an event such as filename, line number, component name, function name.
    • Event “tags”: 28-bit value with user-defined semantics (per-event).
    • Field “tags”: 28-bit value with user-defined semantics (per-field – can be applied to “data” or “struct” elements).
  • You can now define “provider traits” in the manifest (e.g. provider group). If provider traits are used in the manifest, the EventRegister[ProviderName] macro will automatically register them.
  • MC will now report an error if a localized message file is missing a string. (Previously MC would silently generate a corrupt message resource.)
  • MC can now generate Unicode (utf-8 or utf-16) output with the “-cp utf-8” or “-cp utf-16” parameters.

The SDK works in conjunction with previously released SDKs and Visual Studio 2017. Microsoft further notes that you can install this SDK and still also continue to submit your apps that target production versions of Windows 10 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. The Preview SDK can be downloaded from developer section on Windows Insider.

For feedback and updates to the known issues, Microsoft asks that users visit the developer forum, and for new developer feature requests, you can head over to the Windows Platform UserVoice.

Source: Windows Blogs

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