Windows 10 build 20211.1000

Windows 10 build 20211.1000 is the twelfth Insider Preview build of Iron, the 21H1 development semester of Windows as a service. This build was released to Windows Insiders in the Dev Channel on 10 September 2020.

Changes

 * The search box for file types, protocols, and apps when choosing a default app in Settings, which was first introduced with Manganese build 19608 has been made available to all Windows Insiders. It is not enabled by default on a clean installation, and therefore must be enabled through the Vibranium Velocity/ViVeTool utility. To turn it on, type in  from an elevated command prompt and restart.
 * You can now attach and mount a physical hard disk from a WSL 2 distro. This feature enables Windows to be able to read the ext file system that is used in Linux. It can be accessed by typing  into PowerShell.
 * The notification toast improvements that were introduced in build 20161 are enabled by default on clean installations.

Bugs

 * The update process to this build has a chance of hanging for extended periods of time.
 * Live preview doesn't work for pinned site tabs.
 * Some Office applications may either crash or go missing if you update to this build.
 * There's a chance of the Settings app crashing if you open Manage Disks and Volumes.
 * The Linux kernel is not installed when you use the  in the Windows Subsystem for Linux. To workaround this issue, run   to the latest kernel version.
 * Sometimes, when starting up a WSL2 distro, there's a chance of randomly encountering the error “The remote procedure call failed”.
 * On some devices that had this build, the Start menu didn't reflect when there were updates that are pending were present and scheduled restarts were canceled. To install another update, you would have to go to the Windows Update settings page, the system tray icon or restart notification.
 * There's a chance of randomly encountering a BSOD with the error code  when using certain virtualization technologies.
 * The vEthernet adapter used in WSL2 distros can randomly disconnect itself after a certain period of time.
 * You may see generic errors when you install WSL through.