Windows 10 build 9821

Windows 10 build 9821 is the earliest known Technical Preview build of Windows 10. It features the search icon on the taskbar and Task View. This build was leaked on May 11, 2020. Before it was leaked, WinClub.pl had released one screenshot of it. As with other builds in the fbl_partner_eeap branch, it can also boot with the current date without complaining about expired certificates, because it is test-signed, not flight-signed.

Windowed Metro
This build is the first known to possess windowed Metro capability. The title bars of apps in this environment are colored black.

New icons
Some icons (including Explorer's) have been changed to a flatter style.

Aero Changes
DWM-based window animations (particularly window open and close) have been changed to simpler transitions. In addition, the Aero theme's window borders have been made thinner. The Aero Lite theme still possesses the thicker border style.

Windowed Metro
There is a white outline visible when Metro apps are changed to windowed mode.