Windows 10 build 21387 outs in the Dev Channel

The latest preview of Windows 10 (build 21387) removes Internet Explorer 11 and delivers a slew of fixes.

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Windows 10 build 21387
Windows 10 build 21387
  • Microsoft makes available Windows 10 build 21387 in the Dev Channel.
  • The flight removes Internet Explorer 11 from Windows 10.
  • It also disables Task Manager Eco mode and ships with a lot of fixes.

As part of the version 21H2 development, Microsoft is now rolling out Windows 10 build 21387 in the Dev Channel of the Windows Insider Program. This is update number 75 releasing to testers and is a small preview that only includes fixes and a couple of changes.

According to the logs, build 21387 for Windows 10 retires the legacy version of Internet Explorer 11 following the recent announcement where Microsoft revealed that plans to discontinue the browser in 2022.

The Task Manager Eco Mode is now being disabled for the time being to improve the experience and fix several bugs.

Windows 10 build 21387 fixes

Alongside the new changes, this flight ships with a bunch of fixes, including:

  • It fixes an issue in the previous flight where during the upgrade and in the welcome screens displayed after first sign in, the text was unexpectedly using the Times New Roman font.
  • Addresses a problem resulting in some Insiders seeing errors when trying to launch Notepad via the Run dialog.
  • It fixes an issue for WSL users, preventing some Linux GUI apps from launching correctly via the shortcut that is automatically added to the Start menu.
  • Addresses a problem an issue resulting in the reset or change PIN workflows not working.
  • It fixes an issue where for some Insiders, the night light was immediately turning off after being enabled.
  • Addresses a problem in recent flights where you might unexpectedly get a “We can’t find an audio device” error when trying to play audio from a connected Bluetooth speaker.
  • It fixes an issue where explorer.exe might crash after repeated use of the touchpad gesture for switching Virtual Desktops.
  • It Fixes two issues impacting the ability to print using USB printers.
  • Addresses a problem resulting in the Windows Update page potentially becoming unresponsive after clicking Pause Updates.
  • It fixes an issue causing some devices to fail with error code 0xc1900101. While this fix will resolve the problem on some devices, there is a second issue causing the same error code (noted below).
  • Addresses a problem where some devices were re-offered the .NET update after it is installed. 
  • It fixes an issue where some devices would crash with a DPC_WATCHDOG_VIOLATION error when using OneDrive Personal Vault.
  • Addresses a ctfmon.exe crash when using ATOK (a third-party IME) if reconversion was triggered in some win32 apps.

Known issues with build 21387

Microsoft is also pointing out several issues with build 21387, including:

  • The Camera app does not respect the default brightness setting set available on the new Camera Settings page.
  • Windows Search elements no longer display correctly in the dark theme.
  • The “news and interests” taskbar widget has an issue that may occasionally flash in the top left corner of your screen after clicking the button on your taskbar.
  • Microsoft is also working on a fix for a second issue causing some devices to fail when updating this build with error code 0xc1900101.

Microsoft is listing the complete set of improvements, fixes, and issues for Windows 10 Insider Preview build 21387 at the Windows Blog.

Download Windows 10 build 21387

The build 21387 preview is available immediately through the Dev Channel, and it will install automatically. However, you can always get it manually from Settings > Update & security > Windows Update and clicking the Check for updates button.

You can learn more about all the changes available in the current development process of Windows 10 in this guide.

About the author
Avatar for Mauro Huculak

Mauro Huculak is a Windows How-To Expert who started Pureinfotech in 2010 as an independent online publication. He has also been a Windows Central contributor for nearly a decade. Mauro has over 14 years of experience writing comprehensive guides and creating professional videos about Windows and software, including Android and Linux. Before becoming a technology writer, he was an IT administrator for seven years. In total, Mauro has over 20 years of combined experience in technology. Throughout his career, he achieved different professional certifications from Microsoft (MSCA), Cisco (CCNP), VMware (VCP), and CompTIA (A+ and Network+), and he has been recognized as a Microsoft MVP for many years. You can follow him on X (Twitter), YouTube, LinkedIn and About.me. Email him at [email protected].