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Release Date:

8/26/2021

Version:

OS Build 18363.1766

NEW 8/24/2021
IMPORTANT Starting in October 2021, there will no longer be optional, non-security releases (known as "C" releases) for Windows 10, version 1909.  Only cumulative monthly security updates (known as the "B" or Update Tuesday release) will continue for Windows 10, version 1909.

6/15/21
IMPORTANT 
This release includes the Flash Removal Package. Taking this update will remove Adobe Flash from the machine. For more information, see the Update on Adobe Flash Player End of Support.

11/19/20
For information about Windows update terminology, see the article about the types of Windows updates and the monthly quality update types. To view other notes and messages, see the Windows 10, version 1909 update history home page.

Note Follow @WindowsUpdate to find out when new content is published to the release information dashboard.

Highlights

  • Updates an issue that prevents the Windows Movies and TV app from playing some videos (.mp4 files).

  • Updates an issue that resets syncing for Microsoft OneDrive to “Known folders only” after you install a Windows update. 

Improvements and fixes

This non-security update includes quality improvements. Key changes include:

  • Addresses an issue that prevents users from tracking Distributed Component Object Model (DCOM) activation failures.

  • Addresses a threading issue that might cause the Windows Remote Management (WinRM) service to stop working when it is under a high load. This is a client solution; so, apply this update to the affected computers that communicate with WinRM.

  • Addresses an issue that causes the Windows Management Instrumentation (WMI) provider host process to stop working. This occurs because of an unhandled access violation that occurs when using the Desired State Configuration (DSC).

  • Addresses an issue that causes file migration between Distributed File System (DFS) paths that are stored on different volumes to fail. This issue occurs when you implement the migration using PowerShell scripts that use the Move-Item command.

  • Addresses an issue that prevents you from writing to a WMI repository after a low memory condition occurs.

  • Addresses an issue that might prevent you from minimizing an application that uses unthemed windows.

  • Addresses an issue that prevents the Windows Movies and TV app from playing .mp4 media files that contain Pixel Aspect Ration (PAR) information.

  • Addresses an issue that causes Authentication Mechanism Assurance (AMA) to stop working. This issue occurs when you migrate to Windows Server 2016 (or newer versions of Windows) and when using AMA in conjunction with certificates from Windows Hello for Business.

  • Addresses an issue that prevents Secure Launch from working on some devices.

  • Addresses an issue that prevents Code Integrity rules from working correctly when specifying Package Family Name rules in a Code Integrity policy. This issue occurs because of the incorrect handling of case-sensitive names.

  • Addresses an issue that prevents the ShellHWDetection service from starting on a Privileged Access Workstation (PAW) device and prevents you from managing BitLocker drive encryption.

  • Addresses an issue in Windows Defender Exploit Protection that prevents some Microsoft Office applications from working on machines that have certain processors.

  • Addresses an issue that causes the Input Method Editor (IME) toolbar to appear even when the RemoteApp is closed.

  • Addresses an issue with a critical exception that the Open File dialog fails to handle. As a result, a Microsoft Foundation Class (MFC) application unexpectedly closes.

  • Addresses an issue that might occur when you configure the policy, "Delete user profiles older than a specified number of days on system restart". If a user has been signed in for longer than the time specified in the policy, the device might unexpectedly delete profiles at startup.

  • Addresses an issue with the Microsoft OneDrive sync setting "Always keep on this device". The setting is unexpectedly reset to "Known folders only" after you install a Windows update.

  • Addresses an issue that might create duplicate built-in local accounts, such as administrator or guest account, during an in-place upgrade. This issue occurs if you previously renamed those accounts. As a result, the Local Users and Groups MMC snap-in (lusrmgr.msc) appears blank with no accounts after the upgrade. This update removes the duplicate accounts from the local Security Account Manager (SAM) database on the affected machines. If the system detected and removed duplicate accounts, it logs a Directory-Services-SAM event, with ID 16986, in the System event log.

  • Increases the default number of entries in the local security authority (LSA) Lookup Cache to improve lookup performance in high lookup volume scenarios.

  • Addresses stop error 0x1E in srv2!Smb2CheckAndInvalidateCCFFile.

  • Addresses an issue that might cause a system to stop working after a deduplication filter detects damage in a reparse point. This issue occurs because of deduplication driver changes introduced in a previous update.

  • Addresses an issue with using the robocopy command with the backup option (/B) to fix copy failures. This issue occurs when the source files contain Alternate Data Streams (ADS) or Extended Attributes (EA) and the destination is an Azure Files share.

  • Stops running queries against OneSettings APIs from the obsolete Storage Health feature.

If you installed earlier updates, only the new fixes contained in this package will be downloaded and installed on your device. 

Windows Update Improvements

Microsoft has released an update directly to the Windows Update client to improve reliability. Any device running Windows 10 configured to receive updates automatically from Windows Update, including Enterprise and Pro editions, will be offered the latest Windows 10 feature update based on device compatibility and Windows Update for Business deferral policy. This doesn't apply to long-term servicing editions.

Windows 10 servicing stack update - 18363.1766

  • This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. Servicing stack updates (SSU) ensure that you have a robust and reliable servicing stack so that your devices can receive and install Microsoft updates. 

Known issues in this update

Microsoft is not currently aware of any issues with this update.

How to get this update

Before installing this update

Microsoft now combines the latest servicing stack update (SSU) for your operating system with the latest cumulative update (LCU). SSUs improve the reliability of the update process to mitigate potential issues while installing the LCU. For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.

Prerequisite:

You must install the July 13, 2021 SSU (KB5004748) before installing the LCU. 

Install this update

Release Channel

Available

Next Step

Windows Update or Microsoft Update

Yes

Go to Settings > Update & Security > Windows Update. In the Optional updates available area, you’ll find the link to download and install the update.

Windows Update for Business

No

None. These changes will be included in the next security update to this channel.

Microsoft Update Catalog

Yes

To get the standalone package for this update, go to the Microsoft Update Catalog website.

Windows Server Update Services (WSUS)

No

You can import this update into WSUS manually. See the Microsoft Update Catalog for instructions.

If you want to remove the LCU

To remove the LCU after installing the combined SSU and LCU package, use the DISM/Remove-Package command line option with the LCU package name as the argument. You can find the package name by using this command: DISM /online /get-packages.

Running Windows Update Standalone Installer (wusa.exe) with the /uninstall switch on the combined package will not work because the combined package contains the SSU. You cannot remove the SSU from the system after installation.

File information

For a list of the files that are provided in this update, download the file information for cumulative update 5005103

For a list of the files that are provided in the servicing stack update, download the file information for the SSU - version 18363.1766

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