Windows 10 build 9901

Windows 10 build 9901 is a build of Windows 10, which was uploaded to BetaArchive on 14 December 2014.

New features and changes

 * Updated versions of Alarms, Calculator, Camera, Maps, Photos, Sound Recorder, and Windows Store have been included.
 * Contact Support and Get Started apps have been added.

Hidden features
The following hidden features have been found within this build:


 * New tray clock user interface - enabled by creating key  under
 * Hidden lock screen - enabled by setting  to 1 under
 * Enable XAML Start menu - set  to 1 under
 * New volume flyout - enable by setting  to 1 under

Hidden apps
There are a few hidden apps in this build:


 * Windows Default Lock Screen - accessed by running
 * Cloud Experience Host - accessed by running
 * Print Dialog - accessed by running
 * Windows Shell Experience Host - accessed by running

UEFI BIOS
This build can only be installed on machines utilizing UEFI firmware since it hangs on a BIOS system.

Window thumbnail border color
If window auto-colorization is enabled, the window thumbnail borders on the taskbar do not change color even after the wallpaper changes. This issue can be remedied by manually changing the window color through the Control Panel or restarting Windows.