Windows 10 Insider Preview Build 20215 (KB4578846)

If you are a member of the Windows Insider Program, then you ought to be exited what the latest update has to offer. Microsoft recently announced a new preview build 20215 for Windows 10, released on the Dev channel.

New feature: Complete Dark theme support for Windows 10

Microsoft has been having trouble implementing the Dark theme system-wide. Although the Taskbar and the search menu already supported the Dark theme, the search results did not support this theme and displayed the old-style default menu.

old search

Among other fixes, Windows 10 Insider Preview Build 20215 has fixed the issue with the results and now also supports the Dark environment.

after update

This build is a server-side change by Microsoft, hence the size of the update is estimated to be around 3 GB for a 64-Bit architecture, and 2 GB for a 32-Bit. Therefore allow ample time to download and install this update. The computer restarts multiple times during installation.

How to enable system-wide Dark theme in Windows 10

Users have been anticipating Dark themes across all platforms and applications. It not only looks appealing to the eyes but has a softer effect on it as well.

Here is how you can enable the Dark theme once the Windows 10 Insider Preview Build 20215 has been downloaded:

  1. Navigate to the following:
    Start Menu -> Settings -> Personalization -> Colors
  2. Under Choose your color on the right side, open the drop-down menu, and select Dark.
    theme dark

You may now close the Settings application and check the whole theme across Windows, including the new search results!

Other fixes

Microsoft has also addressed a number of issues previously identified in Windows 10. Some of the significant ones are listed below.

  • Addressed the problem of the Windows Security app hanging and crashing.
  • Fixed the problem of Microsoft Edge not opening after system restoration to an older version having the Legacy Edge browser.
  • The issue regarding unprompted cursor movement when typing in Korean IME in some applications has been resolved.

Known issues

It cannot be a Preview build if there are not any problems with it. Although it has not been long since the Insider update was released, Microsoft is already on top of it and aware of a number of different problems regarding this new build.

  • The Windows Update process gets hung for a long time when trying to install this build.
  • Some office applications are crashing or missing from systems after the installation of the Preview Build 20215.
  • Windows Settings are crashing after the update for some Insider users when trying to open the Manage Disks and Volumes.
  • Users are facing some issues with the Linux Kernel for Windows, prompting various errors upon downloading and execution, including the vEthernet adapter getting disconnected in the Windows subsystem for Linux 2 distributions.

How to install Windows 10 Insider Preview Build 20215

If you are subscribed to the Dev channel of the Windows Insider Program, then you shall automatically receive the new update through Windows Updates. However, if you are anxious to receive the update without waiting, here is what you can do.

  1. Navigate to the following location:
    Start Menu -> Settings -> Update & Security -> Windows Update
  2. Now click on Check for updates on the right side and the computer will start scanning for any newly available updates.
    check for updates
  3. When scanned, click on Download now and the installation should begin.
    available update

You can also download the Standalone ISO file from Microsoft’s Insider website. However, you will need to wait as the latest build 20215 is not yet available. Note that you will need to sign in using your registered Microsoft account.

Uninstall the preview update

If this update creates issues for your system, you can easily uninstall it using the following two ways:

Uninstall Windows 10 Insider Preview Build 20215 using the Windows Update History tool

  1. Navigate to the following:
    Start Menu -> Settings –> Update & Security –> Windows Update.
  2. From the right-hand pane, click on View Update History.
  3. Now click on Uninstall updates.
  4. Select Update for Microsoft Windows (KB4578846) and press the Uninstall button. Note that the update name is the same for all the same builds. Hence, any preview updates with a different build but the same name will be removed along with this.

Uninstall Windows 10 Insider Preview Build 20215 using command-line

You can also delete the update by entering several commands in the Command Prompt. Here is how:

  1. Open Command Prompt by typing in cmd in Run.
  2. Enter the following command:
    wmic qfe list brief /format:table
  3. This will show all the updates installed on the computer. Make sure KB4578846 is on the list.
  4. To uninstall the update, run the following command
    wusa /uninstall /kb:4578846
  5. Restart the computer once the update is uninstalled.

You may also leave the Windows Insider Program at any moment following the guide provided.

Cleanup after installing Windows Updates

If you want to save space after installing Windows updates, you can run the following commands:

dism.exe /Online /Cleanup-Image /AnalyzeComponentStore
dism.exe /Online /Cleanup-Image /StartComponentCleanup
Windows image cleanup

You can learn all about the Microsoft Insider Programs and check out how to join and manage them. You can also join the Windows Insider Program without creating or registering your Microsoft account.

Subhan Zafar

Subhan holds a degree in Electrical Engineering and has completed several system and network certifications including Huwaei, Cisco and Microsoft certs. He mostly researches and writes about the Windows world.

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