Windows 10 Enterprise LTSC 2021 known issues and notifications

Article
09/20/2024

Find information on known issues and the servicing status for Windows 10 Enterprise LTSC 2021 and Windows 10 IoT Enterprise LTSC 2021. For immediate help with Windows update issues, click here if you are using a Windows device to open the Get Help app or go to support.microsoft.com. Follow @WindowsUpdate on X for Windows release health updates. If you are an IT administrator and want to programmatically get information from this page, use the Windows Updates API in Microsoft Graph.

Current status as of June 11, 2024

As of June 11, 2024, Home, Pro, Education, and Enterprise editions of Windows 10, version 21H2 have reached end of servicing. Devices running these editions will no longer receive monthly security and quality updates containing protections from the latest security threats.

Windows 10 Enterprise LTSC 2021 and Windows 10 IoT Enterprise LTSC 2021 will continue to have mainstream support until January 12, 2027.

As always, we recommend that you upgrade eligible devices to Windows 11. For information about servicing timelines and lifecycle, see Windows 11 release information, Windows 10 release information, Windows Lifecycle FAQ, and Microsoft Lifecycle Policy search tool.

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Known issues

See open issues, content updated in the last 30 days, and information on safeguard holds. To find a specific issue, use the search function on your browser (CTRL + F for Microsoft Edge).

Summary	Originating update	Status	Last updated
August 2024 security update might impact Linux boot in dual-boot setup devices This issue might impact devices with dual-boot setup for Windows and Linux when SBAT setting is applied	OS Build 19044.4780 KB5041580 2024-08-13	Mitigated	2024-09-20 12:41 PT
Enterprise customers might be unable to use Microsoft Connected Cache This issue affects Windows devices which use the DHCP Option 235 to configure the Microsoft Connected Cache endpoint	OS Build 19044.4046 KB5034763 2024-02-13	Mitigated	2024-04-05 11:43 PT

Issue details

August 2024

August 2024 security update might impact Linux boot in dual-boot setup devices

Status	Originating update	History
Mitigated	OS Build 19044.4780 KB5041580 2024-08-13	Last updated: 2024-09-20, 12:41 PT Opened: 2024-08-21, 18:33 PT

After installing the August 2024 Windows security update, (KB5041580) or the August 2024 preview update, you might face issues with booting Linux if you have enabled the dual-boot setup for Windows and Linux in your device. Resulting from this issue, your device might fail to boot Linux and show the error message “Verifying shim SBAT data failed: Security Policy Violation. Something has gone seriously wrong: SBAT self-check failed: Security Policy Violation.”

The August 2024 Windows security and preview updates apply a Secure Boot Advanced Targeting (SBAT) setting to devices that run Windows to block old, vulnerable boot managers. This SBAT update will not be applied to devices where dual booting is detected. On some devices, the dual-boot detection did not detect some customized methods of dual-booting and applied the SBAT value when it should not have been applied.

IMPORTANT: This known issue only occurs with the installation of the August 2024 security and preview updates. The September 2024 security update (KB5043064) and later updates do not contain the settings that caused this issue. If you install the September 2024 update, you don’t need to apply the workaround below.

Workaround:

If your Linux becomes unbootable after installing the August 2024 security or preview updates, you can recover your Linux system by following these instructions.

Important: This documentation contains information about how to modify the registry. Make sure that you back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, see How to back up and restore the registry in Windows. Also, note that modifying firmware settings incorrectly might prevent your device from starting correctly. Follow these instructions carefully and only proceed if you are confident in your ability to do so.

a) Disable Secure Boot:

Boot into your device’s firmware settings.
Disable Secure Boot (steps vary by manufacturer).

b) Delete SBAT Update:

Boot into Linux.
Open the terminal and run the below command:

sudo mokutil --set-sbat-policy delete

Enter your root password if prompted.
Boot into Linux once more.

c) Verify SBAT Revocations:

In the terminal, run the below command:

mokutil --list-sbat-revocations

Ensure the list shows no revocations.

d) Re-enable Secure Boot:

Reboot into the firmware settings.
Re-enable Secure Boot.

e) Check Secure Boot Status:

Boot into Linux. Run the below command:

 mokutil --sb-state

The output should be “SecureBoot enabled”. If not, retry step d).

f) Prevent Future SBAT Updates in Windows:

Boot into Windows.
Open Command Prompt as Administrator and run:

reg add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecureBoot\SBAT /v OptOut /d 1 /t REG_DWORD

At this point, you should now be able to boot into Linux or Windows as before. It’s a good time to install any pending Linux updates to ensure your system is secure.

NOTE: On Windows-only systems, after installing the September 2024 or later updates, you can set the registry key documented in CVE-2022-2601 and CVE-2023-40547 to ensure the SBAT security update is applied. On systems that dual-boot Linux and Windows, there are no additional steps necessary after installing the September 2024 or later updates.

Next Steps: We are working on a final resolution that will be available in a future Windows update. We recommend you install the September 2024 update or later Windows updates to avoid this issue.

Affected platforms:

Client: Windows 11, version 23H2; Windows 11, version 22H2; Windows 11, version 21H2; Windows 10, version 22H2; Windows 10, version 21H2; Windows 10 Enterprise 2015 LTSB
Server: Windows Server 2022; Windows Server 2019; Windows Server 2016; Windows Server 2012 R2; Windows Server 2012

April 2024

Enterprise customers might be unable to use Microsoft Connected Cache

Status	Originating update	History
Mitigated	OS Build 19044.4046 KB5034763 2024-02-13	Last updated: 2024-04-05, 11:43 PT Opened: 2024-04-05, 11:09 PT

After installing the February 2024 Windows security update (KB5034763), released February 13, 2024, or later updates, some Windows devices which use the DHCP Option 235 for discovery of Microsoft Connected Cache (MCC) nodes in their network might be unable to use the MCC nodes. Instead, these Windows devices will download updates and apps from the public internet and IT administrators would see increased download traffic on their internet routes.

Home users of Windows are unlikely to experience this issue, as Microsoft Connected Cache configured via DHCP Option 235 is more commonly used in enterprise environments.

Workaround:

Option1: Configure Microsoft Connected Cache endpoint in DOCacheHost policy as indicated in Cache hostname. Additionally, DOCacheHostSource has to be set to 1 or removed as indicated in Cache hostname source. Note that by default, the DOCacheHost and DOCacheHostSource policies have no value.
Option2: This issue can also be mitigated using Group Policies available through our support channel. Organizations can request help through Support for business.

Next steps: We are working on a resolution and will provide an update in an upcoming release.

Affected platforms:

Client: Windows 10, version 21H2, Windows 10, version 22H2
Server: None

Report a problem with Windows updates

To report an issue to Microsoft at any time, use the Feedback Hub app. To learn more, see Send feedback to Microsoft with the Feedback Hub app.

Need help with Windows updates?

Search, browse, or ask a question on the Microsoft Support Community. If you are an IT pro supporting an organization, visit Windows release health on the Microsoft 365 admin center for additional details.

For direct help with your home PC, use the Get Help app in Windows or contact Microsoft Support. Organizations can request immediate support through Support for business.

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