Windows 10 build 21301.1000

Build of Cobalt
OS familyWindows 10 (NT 10.0)
Version number10.0
Build number21301
Build revision1000
Architecturex86, x64, ARM64
Build labrs_prerelease
Compiled on2021-01-23
Expiration date
Timebomb2021-10-31 (+281 days)
Home (China, N, Single Language)
Pro (China Only, N, Single Language)
Pro Education (N)
Pro (N) for Workstations
Education (N)
Enterprise (N, (N) Evaluation, G (N))
Enterprise multi-session
IoT Enterprise
Product key
Use a Windows 10 Retail serial
About dialog
21301 Winver.png
TCB.png TCBGallery.png

Windows 10 build 21301.1000 is the fifth Insider Preview build of Cobalt, the 21H2 development semester of Windows as a service. This build was released on 27 January 2021 to all Windows Insiders on the Dev Channel.[1]

It is the last build to include the Legacy Edge web browser, as in the next build it has been removed entirely and replaced with Chromium Edge.

Changes[edit | edit source]

Intel Thread Director support[edit | edit source]

This is the first known build to enable the MSR_IA32_HW_FEEDBACK_THREAD_CONFIG MSR to support the Intel Thread Director, a feature first introduced by Intel Core 12th generation processors that helps schedule programs across higher performance and power efficient cores.[2]

User interface[edit | edit source]

Taskbar[edit | edit source]

Right-clicking on files within taskbar jump lists now allows the user to open their respective source locations.

Touch keyboard[edit | edit source]

Undocking the keyboard on 2-in-1 devices now switches to a smaller keyboard layout that can be moved across the screen. Updated symbols for both small and large modes have been introduced, and a visual feedback icon is now present at the left-hand side of the touch keyboard UI whenever the user shifts focus onto any applicable password field. An updated keyboard layout featuring Esc, Tab ↹, and ⊞ Win keys has been introduced when using Windows on a 12" display, and currency support was added for the N’Ko script's associated keyboard layout

Desktop Window Manager[edit | edit source]

The animation speed of the updated window animations first introduced as part of build 21277 has been slightly adjusted.

Miscellaneous[edit | edit source]

  • Internal dictionaries for existing system languages were updated to provide more accurate text prediction and spell-checking results.
  • Modifying the touchpad enablement states in the Settings application no longer requires administrative elevation.

Bugs[edit | edit source]

News and interests[edit | edit source]

  • The taskbar button's layout is reset to "Show icon and text" after upgrading to this build.
  • Sometimes the flyout cannot be dismissed with pen.
  • The taskbar button can show stale information each time users log into their account.
  • The flyout shows content in a single column before quickly switching to double column.
  • The taskbar button's text can look pixelated in high resolution screens.
  • Attempting to share content dismisses the flyout.

General[edit | edit source]

  • The update process to this build has a chance of hanging for extended periods of time.
  • There's a chance that the upgrade process to this build may fail with an IRQL_NOT_LESS_OR_EQUAL BSOD.
  • The reliability of the Start menu and other modern apps may be affected in this build.
  • Miracast users may experience very low frame rates in this build.
  • Live preview doesn't work for pinned site tabs on some machines, a gray window is seen instead of the intended content.

Gallery[edit | edit source]

References[edit | edit source]