Windows 11, version 21H2 known issues and notifications

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09/20/2024

Find information on known issues and the status of the Windows 11, version 21H2 rollout. 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 (formerly Twitter) 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.

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Current status as of October 10, 2023

As of October 10, 2023, Home and Pro editions of Windows 11, version 21H2 have reached end of servicing. The October 2023 security update, released on October 10, 2023, is the last update available for these editions. After this date, devices running these editions will no longer receive monthly security and preview updates containing protections from the latest security threats. Enterprise, Education, IoT Enterprise, and Enterprise multi-session editions for this version will reach end of servicing on October 8, 2024 and will receive security updates until then.

To help keep you protected and productive, Windows Update will automatically initiate a feature update for Windows 11 consumer devices and non-managed business devices that are at, or within several months of reaching, end of servicing. This keeps your device supported and receiving monthly updates that are critical to security and ecosystem health. For these devices, you will be able to choose a convenient time for your device to restart and complete the update.

As always, we recommend that you update your devices to the latest version of Windows 11. For detailed information, see the Windows 11, version 21H2 end of servicing (Home & Pro) lifecycle page. For information about servicing timelines and lifecycle, see Windows 11 release information, Lifecycle FAQ - Windows, and Microsoft Lifecycle Policy search tool.

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Known issues

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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 22000.3147 KB5041592 2024-08-13	Mitigated	2024-09-20 12:30 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 22000.3147 KB5041592 2024-08-13	Last updated: 2024-09-20, 12:30 PT Opened: 2024-08-21, 18:33 PT

After installing the August 2024 Windows security update, (KB5041592) 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 (KB5043067) 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

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