Windows 10 build 21387 (co release)

Windows 10 build 21387 (co_release) is the nineteenth Insider Preview build of Cobalt, the 21H2 development semester of Windows as a service. This build was released on 21 May 2021 to all Windows Insiders on the Dev Channel.

Changes

 * Internet Explorer 11 has been removed from Windows 10 development cycles starting with this build. Attempting to run its executable file will open Edge instead. It is still possible to run Internet Explorer if   is replaced with a copy from an older build or renaming/deleting the   folder.
 * The "Eco mode" experimental Task Manager feature introduced in build 21364 has been removed.

News and interests

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

Camera Settings

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

Installation

 * 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  due to a second issue different from that in build 21382.

OOBE

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

General

 * 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.