Windows 10 Build 19645 (Fast Ring)

Microsoft is releasing a new Manganese build of Windows 10. Supposed to eventually become '20H2', it doesn't include new features, and includes a few improvements and fixes. Also, there is an update for the Your Phone app.

What's new in Windows 10 Build 19645

General changes & improvements

• 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 3^rd 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.

Fixes

• 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).

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).

Your Phone app’s audio controls feature now rolling out to the public

This feature lets you control your music and audio apps from the Your Phone app. Now you can access and control the audio apps playing from your phone directly within the app, without needing to split your attention between devices or breaking your workflow. Your audio tracks will stay in sync between your phone and PC, and you can switch between multiple sources using the dropdown in the player.

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The Fast ring now reflects the latest changes made to Windows code base. It is a work-in-progress, so the changes you see in Fast Ring releases may not appear in the upcoming feature update. Due to the changes coming to the Fast Ring builds, it is possible that will see some of Windows 10X features on Desktop. Microsoft may want to roll out Windows 10X's features to test them with a larger number of devices. So we can expect to see some features which will never appear in stable Windows 10 versions on Desktop.

If you have configured your device to receive updates from the Fast Ring ring, open Settings - > Update & recovery and click on the Check for Updates button on the right. This will install the latest available Insider Preview of Windows 10.