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 11 May 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 because it is test-signed, not flight-signed. But the system will remind you to install a newer build if you didn't set the time and turn off network adapters while installing.

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.

Branding
This build uses the "Windows Technical Preview" branding on the desktop and "Windows" branding in winver instead of "Windows 8.1" and "Windows 8" in those areas respectively.

Window thumbnail color error
Window thumbnails on the taskbar do not change color, but they can change it after the computer restarts.

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

Bug with the metro
Dragging a window in full-screen mode in metro apps will result in metro transitions from Windows 8.1.

Error with window size when transferring / copying files
Apparently this build has an error with the window size when transferring / copying files