Windows 10 build 21387

10.0.21387.1.co_release.210518-1436
Build of Windows 10 Cobalt
10.0.21387.1.co_release.210518-1436
OS family
Architecturex86, x64, ARM64
Compiled2021-05-18
Timebomb2021-10-31 (+166 days)
Works in
About
21387 winver.png
SKUs
Home
Home China
Home N
Home Single Language
Pro
Pro N
Pro Single Language
Pro China Only
Pro Education
Pro Education N
Pro for Workstations
Pro N for Workstations
Education
Education N
Enterprise
Enterprise Evaluation
Enterprise G
Enterprise G N
Enterprise multi-session
Enterprise N
Enterprise N Evaluation
IoT Enterprise
Team
Cloud
Cloud N
TCB.png TCBGallery.png

Windows 10 build 21387 is the nineteenth Insider Preview build of Cobalt. This build was released on 21 May 2021 to all Windows Insiders on the Dev Channel.

Changes[edit | edit source]

  • Internet Explorer 11 has been removed from Windows 10 development cycles starting with this build. Attempting to run its executable file (iexplore.exe) will open Edge instead. It is still possible to run Internet Explorer if ieframe.dll is replaced with a copy from an older build.
  • The "Eco mode" experimental Task Manager feature introduced in build 21364 has been removed.

Bugs[edit | edit source]

News and interests[edit | edit source]

  • The flyout might occasionally flash in the screen's top left corner when opened.

Camera Settings[edit | edit source]

  • The Camera app does not respect the brightness adjustments made to a camera under its respective page.

Installation[edit | edit source]

  • The update process to this build has a chance of hanging for extended periods of time.
  • Some devices might fail to upgrade to this build with error code 0xc1900101 due to a second issue different from that in build 21382.

OOBE[edit | edit source]

  • The OOBE may use an incorrect font when this build is ran under Simplified Chinese language pack.

General[edit | edit source]

  • Certain parts of Search, including the File Explorer search box, are not displaying correctly in the dark theme.
  • The icons for Microsoft Edge and File Explorer in the taskbar are swapped in clean installations.

Gallery[edit | edit source]

External links[edit | edit source]