While the stable version of Windows 10 21H1 will be released in Spring 2021, this is the second update released for 21H1.
Improvements and fixes
Ths improvements and fixes included in version 21H1 are the same as mentioned in the 20H2 update post. Even the Knowledge Base help article is the same, KB5000802. Here are the fixed mentioned on the Windows blog:
How to upgrade to Windows 10 21H1 Build 19043.867
Make sure that you are on a beta channel and then follow the instructions below to install this update on your computer. Security updates to the Windows Shell, Windows Fundamentals, Windows Management, Windows Apps, Windows User Account Control (UAC), Windows Virtualization, Windows Kernel, the Microsoft Graphics Component, Internet Explorer, Microsoft Edge Legacy, and Windows Media. To install this update using Windows Update, please go to Start Menu –> Settings –> Update & Security –> Windows Update. In the right-hand pane, click on the Check for updates button. You will then be able to see the update and should install it automatically.
Uninstall KB5000802 using command-line
Since we have installed this update using Windows Update, it will not be listed in the list of updates but you can see it in the command line: Restart your computer once the update is uninstalled.
Cleanup after installing Windows Updates
If you want to save space after installing Windows updates, you can run the following commands: