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Release Date:

5/11/2021

Version:

OS Build 14393.4402

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 1607 update history home page. 

Highlights

  • Updates an issue in Task Scheduler that causes monthly tasks and tasks scheduled for 0 UTC to occur at the wrong time.

  • Updates to improve Windows OLE (compound documents) security.

  • Updates security for Bluetooth drivers.

Improvements and fixes

This security update includes quality improvements. Key changes include:

  • Addresses an issue with evaluating the compatibility status of the Windows ecosystem to help ensure application and device compatibility for all updates to Windows.

  • Provides a DWORD registry key to address a performance issue that might occur when you use the Background Intelligent Transfer service (BITS) to download many files. Set the DWORD registry key as “HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\BITS\EnableLargeBuffer= 0x1”. After you set the registry key, restart the machine, or restart BITS to enable the use of large buffer size and file size incrementing.

  • Addresses an issue in Task Scheduler that causes monthly tasks and tasks scheduled for 0 UTC to occur at the wrong time.

  • Security updates to Windows App Platform and Frameworks, the Microsoft Scripting Engine, and the Windows Silicon Platform.

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

For more information about the resolved security vulnerabilities, please refer to the new Security Update Guide website.

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.

Known issues in this update

Symptom

Workaround

After installing updates released April 22, 2021 or later, an issue occurs that affects versions of Windows Server that are in use as a Key Management Services (KMS) host. Client devices running Windows 10 Enterprise LTSC 2019 and Windows 10 Enterprise LTSC 2016 might fail to activate. This issue only occurs when using a new Customer Support Volume License Key (CSVLK). 

Note This does not affect activation of any other version or edition of Windows. 

Client devices that are attempting to activate and are affected by this issue might receive the error, "Error: 0xC004F074. The Software Licensing Service reported that the computer could not be activated. No Key Management Service (KMS) could be contacted. Please see the Application Event Log for additional information."

Event Log entries related to activation are another way to tell that you might be affected by this issue. Open Event Viewer on the client device that failed activation and go to Windows Logs > Application. If you see only event ID 12288 without a corresponding event ID 12289, this means one of the following:

  • The KMS client could not reach the KMS host.

  • The KMS host did not respond.

  • The client did not receive the response.

For more information on these event IDs, see Useful KMS client events - Event ID 12288 and Event ID 12289.

This issue is resolved in KB5010359.

How to get this update

Before installing this update

Microsoft strongly recommends you install the latest servicing stack update (SSU) for your operating system before installing the latest cumulative update (LCU). SSUs improve the reliability of the update process to mitigate potential issues while installing the LCU and applying Microsoft security fixes. For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.

If you are using Windows Update, the latest SSU (KB5001402) will be offered to you automatically. To get the standalone package for the latest SSU, search for it in the Microsoft Update Catalog. 

Install this update

Release Channel

Available

Next Step

Windows Update and Microsoft Update

Yes

None. This update will be downloaded and installed automatically from Windows Update.

Windows Update for Business

Yes

None. This update will be downloaded and installed automatically from Windows Update in accordance with configured policies.

Microsoft Update Catalog

Yes

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

Windows Server Update Services (WSUS)

Yes

This update will automatically sync with WSUS if you configure Products and Classifications as follows:

Product: Windows 10

Classification: Security Updates

File information

For a list of the files that are provided in this update, download the file information for cumulative update 5003197. 

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