Microsoft releases Windows 10 build 19645 to the Fast ring – here’s what’s new

It's Wednesday, and that means that it's time for a new Windows 10 Insider Preview in the Fast ring. As has been the case for months now, there isn't anything new in terms of features. Build 19645 is once again from the mn_release branch, and we likely won't see anything new until the return of rs_prerelease.

That should happen this month though, so if you're looking to get excited about something, you just have to hold out for a little bit longer. Those will be from the Iron branch, which is better known as 21H1. The one we're seeing now, mn_release, is the Manganese branch, and while that was going to be the 20H2 release for Windows 10X, and also the RTM, it's not anymore. 20H2 is going to be an enablement package like 19H2 was, so the fact that new builds are coming from a release branch right now is pretty much Microsoft going through the motions.

As always, there's a list of fixes, improvements, and known issues in the build. Here are the general changes:

  • We changed the servicing model for the Linux kernel inside of Windows Subsystem for Linux 2 distributions. This build includes this change to remove the Linux kernel from the Windows image, and instead have it be serviced via Microsoft Update, the same way that 3rd party drivers (like graphics, or touchpad drivers) are installed and updated on your machine today. For full details please read this blog post on the Windows Command Line blog and for information about the kernel version please view the kernel docs page here.
  • Support for Nested Virtualization on AMD processors is now available. Being an early release we recommend you read this blog post for details on what platforms currently work as well as how to enable the feature.

Here's what got fixed and improved:

  • We’ve fixed an issue where some devices booting from eMMC storage bugchecked when resuming from hibernate.
  • We fixed multiple Japanese and Chinese IME issues that impacted IME mode switching within applications and Windows notification area.
  • We’ve fixed an issue where taskbar preview thumbnails weren’t rendering consistently (showing a blank area).
  • We fixed an issue resulting in the handwriting input panel not appearing in certain text fields after being tapped with a pen.
  • We fixed an issue where resizing a snapped application in tablet mode would minimize the app to the taskbar instead of adjusting the app size.
  • We fixed an issue where Windows Hello Setup would crash if facial recognition was already set up and you chose the Improve Recognition button.
  • We fixed an issue for some users where your PC wouldn’t recognize it when you inserted a smart card (event log showing error 621).

Here are the known issues:

  • We’re looking into reports of the update process hanging for extended periods of time when attempting to install a new build.
  • We’re working on fixing an issue for a future Insider Preview build where in Settings > Privacy, the Documents and Downloads sections show a broken icon next to their page name (just a rectangle).

As always, you can grab today's build from Windows Update. If you're not on the Fast ring yet, you can get started via the Windows Insider Program tab.

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