Today, we released a new Windows 10 SDK Preview and the associated Windows 10 Mobile emulators (Build 10563), to be used in conjunction with Windows 10 Insider Preview (Build 10565). The Preview SDK is a pre-release and cannot be used in a production environment. Please only install the SDK on your test machine. The Preview SDK Build 10563 contains bug fixes and under development changes to the API surface area. If you are working on an application that you need to submit to the store, you should not install the preview. The Preview SDK can be downloaded from the Windows 10 Developer Tools page.
Read more: Windows 10 SDK Preview Build 10563 Released | Building Apps for Windows