Earlier this month, Microsoft said that it won't be releasing any Windows 10 cumulative update previews for the month of December, but December isn't until tomorrow, and a new cumulative update is here. In fact, it's the exact same cumulative update that was released to Windows Insiders a week ago.

The update is for those that are running one of the two latest versions of Windows 10, 20H2 or 2004. It's KB4586853, and it brings the build number to 19042.662 or 19041.662, respectively. You can manually download it here, and these are the highlights:

  • Updates an issue that causes Narrator to stop responding after you unlock a device if Narrator was in use before you locked the device.
  • Updates an issue that prevents you from finding certain Microsoft Xbox consoles on a Windows device.
  • Updates an issue that fails to display the Microsoft Xbox Game Bar app controls on supported monitors. This issue occurs in certain Microsoft DirectX® 9.0 (DX9) games that are running with Variable Refresh Rate enabled on these monitors.
  • Updates an issue with USB 3.0 hubs. A device connected to the hub might stop working when you set the device to hibernate or restart the device.
  • Updates an issue that randomly changes the input focus of edit controls when using the Japanese IME or the Chinese Traditional IME.
  • Updates an issue that makes the touch keyboard unstable in the Mail app.
  • Improves the visual quality of Windows Mixed Reality headsets that run in lower resolution mode.
  • Updates an issue that prevents the PDF24 app, version 9.1.1, from opening .txt files.

Here's the full list of fixes:

  • Updates Internet Explorer’s About dialog to use the standard modern dialog.
  • Addresses an issue that causes Narrator to stop responding after you unlock a device if Narrator was in use before you locked the device.
  • Addresses an issue that fails to display the local account groups in the localized language even after you deploy the language pack.
  • Addresses an issue that prevents a user from finding certain Microsoft Xbox consoles on a Windows device.
  • Addresses an issue that displays a black screen to Windows Virtual Desktop (WVD) users when they attempt to sign in.
  • Addresses an issue with a certain COM API that causes a memory leak.
  • Addresses an issue that fails to display the Microsoft Xbox Game Bar app controls on supported monitors. This issue occurs in certain Microsoft DirectX® 9.0 (DX9) games that are running with Variable Refresh Rate enabled on these monitors.
  • Addresses an issue that prevents the touch keyboard from opening in Universal Windows Platform (UWP) apps when USB devices are connected.
  • Addresses an issue with USB 3.0 hubs. A device connected to the hub might stop working when you set the device to hibernate or restart the device.
  • Addresses an issue that crops the touch keyboard when you use a Remote Desktop Connection on a device that has a different screen resolution.
  • Addresses an issue with excessive network traffic that occurs when you use the Open File dialog box in File Explorer and browse to a shared folder that has the Previous Version feature available.
  • Addresses an issue that causes the ImmGetCompositionString() function to return the full-width Hiragana when using the Microsoft Input Method Editor (IME) for Japanese instead of returning the half-width Katakana.
  • Addresses an issue that prevents JumpList items from functioning. This occurs when you create them using the Windows Runtime (WinRT) Windows.UI.StartScreen API for desktop applications that are packaged in the MSIX format.
  • Addresses an issue that prevents applications from receiving the Shift and Ctrl keystroke events when the Bopomofo, Changjie, or Quick Input Method Editors (IME) are in use.
  • Addresses an issue that randomly changes the input focus of edit controls when using the Japanese IME or the Chinese Traditional IME.
  • Addresses an issue that prevents you from signing in on certain servers. This occurs when you enable a Group Policy that forces the start of a computer session to be interactive.
  • Addresses an issue that fails to set the desktop wallpaper as configured by a GPO when you specify the local background as a solid color.
  • Addresses an issue with the Microsoft Pinyin IME that unexpectedly dismisses the candidate pane when you type certain phrases.
  • Addresses an issue that fails to send the Shift keyup event to an application when you use the Japanese IME.
  • Addresses an issue that renders Kaomoji incorrectly on the emoji panel.
  • Addresses an issue that makes the touch keyboard unstable in the Mail app.
  • Addresses an issue that enters unexpected characters, such as half-width Katakana, when you type a password while the IME is in Kana input mode.
  • Addresses an issue that might fail to pair certain MIDI devices that connect using Bluetooth Low Energy (LE).
  • Addresses a runtime error that causes Visual Basic 6.0 (VB6) to stop working when duplicate windows messages are sent to WindowProc().
  • Addresses an issue that generates a 0x57 error when the wecutil ss /c: command is used to update an Event Forwarding subscription.
  • Addresses an issue that causes applications to fail when they call the LookupAccountSid() API. This occurs after migrating accounts to a new domain whose name is shorter than the name of the previous domain.
  • Addresses an issue in which loading a Code Integrity Policy causes PowerShell to leak a large amount of memory.
  • Addresses an issue that causes a system to stop working during startup. This occurs when the CrashOnAuditFail policy is set to 1 and command-line argument auditing is turned on.
  • Addresses an issue that causes the Microsoft Management Console (MMC) Group Policy application to stop working when you are editing the Group Policy Security settings. The error message is, “MMC cannot initialize the snap-in.”
  • Addresses an issue that fails to free a system’s non-paged pool and requires a restart of the system. This occurs when running 32-bit applications with the Federal Information Processing Standard (FIPS) mode enabled.
  • Addresses an issue that might prevent updates from installing and generates an “E_UNEXPECTED” error.
  • Addresses an issue that causes the “I forgot my Pin" functionality on the lock screen to fail. This failure occurs if the user has signed in using a username and password and the DontDisplayLastUserName or HideFastUserSwitching policy settings are enabled.
  • Addresses an issue that prevents access to Azure Active Directory (AD) using the Google Chrome browser because of a Conditional Access policy error.
  • Improves the visual quality of Windows Mixed Reality headsets that run in lower resolution mode.
  • Extends Microsoft Defender for Endpoint support to new regions.
  • Enables a new Hardware-enforced Stack Protection feature called shadow stacks on supported hardware. This update allows applications to opt in to user-mode shadow stack protection, which helps harden backward-edge control-flow integrity and prevents return-oriented programming-based attacks.
  • Addresses an issue in the Microsoft Remote Procedure Call (RPC) runtime that causes the Distributed File System Replication (DFSR) service to stop responding. This issue generates log events for DFS Replication (5014), RPC (1726), and no reconnection (5004) for a default timeout of 24 hours with no replication.
  • Adds the touch keyboard to the allowed apps list, and it now works in multi-app assigned access mode.
  • Addresses an issue that prevents the PDF24 app, version 9.1.1, from opening .txt files.
  • Addresses an issue that might cause a non-paged pool memory leak in some scenarios.
  • Addresses an issue that allows an app that has been blocked from hydrating files to continue hydrating files in some cases.
  • Addresses an issue that might cause a memory leak in bindflt.sys when copying files in a container scenario.
  • Addresses an issue with Active Directory Certificate Services (AD CS) that fails to submit Certificate Transparency (CT) logs when they are enabled.
  • Addresses an issue in which cluster validation tests internal switches that are not for cluster use and re-communication.
  • Addresses an issue that causes stop error 0x27 when you attempt to sign in to a device that is not in a domain using credentials for a device that is in the domain.

There are also two known issues:

Symptom Workaround
Users of the Microsoft Input Method Editor (IME) for Japanese or Chinese languages might experience issues when attempting various tasks. You might have issues with input, receive unexpected results, or might not be able to enter text. For more information about the issues, workaround steps, and the currently resolved issues, please see KB4564002

System and user certificates might be lost when updating a device from Windows 10, version 1809 or later to a later version of Windows 10. Devices will only be impacted if they have already installed any Latest cumulative update (LCU) released September 16, 2020 or later and then proceed to update to a later version of Windows 10 from media or an installation source which does not have an LCU released October 13, 2020 or later integrated. This primarily happens when managed devices are updated using outdated bundles or media through an update management tool such as Windows Server Update Services (WSUS) or Microsoft Endpoint Configuration Manager. This might also happen when using outdated physical media or ISO images that do not have the latest updates integrated.

Note Devices using Windows Update for Business or that connect directly to Windows Update are not impacted. Any device connecting to Windows Update should always receive the latest versions of the feature update, including the latest LCU, without any extra steps.

If you have already encountered this issue on your device, you can mitigate it within the uninstall window by going back to your previous version of Windows using the instructions here. The uninstall window might be 10 or 30 days depending on the configuration of your environment and the version you’re updating to. You will then need to update to the later version of Windows 10 after the issue is resolved in your environment. Note Within the uninstall window, you can increase the number of days you have to go back to your previous version of Windows 10 by using the DISM command /Set-OSUninstallWindow. You must make this change before the default uninstall window has lapsed. For more information, see DISM operating system uninstall command-line options.

We are working on a resolution and will provide updated bundles and refreshed media in the coming weeks.

This is an optional update, meaning that you'll need to opt into installing it before Windows Update will install it. If you don't take it, these fixes will be rolled into next month's mandatory Patch Tuesday update.