Want a quick overview?: Watch the Windows 11 release note video for this update. |
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Announcements and messages
This section provides key notifications related to this release, including announcements, change logs, and end-of-support notices.
Important
Windows 11, version 24H2 Home and Pro has reached end of updates. The October 2026 monthly security update is the last update available for these editions. Devices running these editions will no longer receive monthly security and non-security preview updates containing protections from the latest security threats. To stay protected and up to date, we recommend you upgrade to the latest version of Windows 11.
Windows Secure Boot certificate expiration
Secure Boot certificate updates remain in progress as Microsoft transitions devices from certificates that began expiring in 2026 to newer certificates. Devices that have not yet received the newer certificates can continue to start and receive standard Windows updates. Microsoft will continue delivering the newer Secure Boot certificates to eligible devices through Windows Update.
Improvements
This update includes improvements from the following previously released updates:
- September 8, 2026-KB5124008 (OS Builds 26200.9445 and 26100.9445)
- September 14, 2026—KB5129195 (OS Builds 26200.9457 and 26100.9457) Out-of-band
- September 22, 2026—KB5124010 (OS Builds 26300.9550, 26200.9550, and 26100.9550)
The following summary outlines key quality improvements addressed by this update. The bold text within the brackets indicates the item or area of the change.
[Security updates] This update provides security improvements. For more information about the security vulnerabilities resolved by this update, see the Security Update Guide.
[Secure Boot] This update continues the deployment of updated Secure Boot certificates using the latest high-confidence targeting data to identify eligible devices that are ready to automatically receive the new certificates. Deployment through Windows Update remains ongoing across supported devices.
[Windows Explorer (Known issue)] Fixed This update fixes an issue that affects Windows Explorer in multi-user environments, such as Azure Virtual Desktop and FSLogix. After sign-in, Explorer.exe might fail to start or repeatedly crash, causing a black screen.
[Audio (known issue)] Fixed This update fixes an issue that affects AC-3 audio playback in some applications.
[Always On VPN] This update fixes an issue that affects Always On VPN connections after installing KB5124008. When automatic protocol selection or protocol fallback was configured, affected VPN connections could remain stuck in a Connecting state or fail to connect after an initial connection attempt failed. In some cases, subsequent connection attempts could display the error, "The specified port is already in use."
[Storage Spaces] This update fixes an issue that affects tiered Storage Spaces Direct virtual disks. Some virtual disks might fail to come online after installing certain security updates, making dependent clustered workloads unavailable.
[Date and Time] This update introduces the new (UTC-05:00) Manitoba time zone to support Manitoba’s November 1, 2026, time zone change.
[ReFS security] This update adds auditing and optional policy controls for ReFS volumes on externally attached storage devices. Auditing is enabled by default, while enforcement controls remain disabled by default to give administrators time to evaluate and prepare for future security hardening changes. To learn more, see KB5130741.
[Printing] This update resolves an issue where printing could fail in some applications and on devices using RAW or Generic Text Only printer drivers after installing the August 2026 security update.
[Gaming] This update fixes an issue that could cause mouse input to stutter in some games.
[Windows Hello] This update fixes an issue where fingerprint sign-in might not work after a cold boot on some devices.
If you've already installed previous updates, your device will download and install only the new updates included in this package.
Components updates
AI components
This release updates the following AI components to version 1.2608.951.0: Image Search, Content Extraction, Semantic Analysis, and Settings Model. To learn more, see Release information for AI components.
Servicing stack update
Includes KB5127647 (Build 26100.9703), which improves the reliability of the Windows update installation process. To learn more about SSUs, see Servicing stack updates.
Known issues in this update
USB audio devices might fail to start or produce no sound
Symptoms
After installing the September 8, 2026, Windows security update (KB5124012), some USB Audio Class 1.0 devices might fail to start or produce audio. Affected devices might experience one or more of the following symptoms:
The device displays an error in Device Manager: "This device cannot start (Code 10).”
No audio output.
Volume controls are unresponsive or remain at zero.
Sound settings are unresponsive or unavailable.
Some devices might function in standard stereo configurations but fail when using multichannel audio features, including 8-channel or 3D audio modes. Some customers have reported that they're able to restore audio in these cases by switching to 2-channel mode.
This issue is limited to USB Audio Class 1.0 devices.
Resolution
This issue is partially resolved in the out-of-band (OOB) update released on September 14, 2026, (KB5129195). This OOB update resolves the symptoms experienced on devices using 8-channel or 3D audio modes. Microsoft is working to address the other symptoms and will provide more information when it is available.
IT administrators who need an immediate workaround for the symptoms not addressed yet by the OOB update should contact Microsoft Support for Business for assistance.
How to get this update
Deployment
If you deploy dynamic updates such as this update to an existing Windows image, ensure the boot.stl file is included as part of the installation media. Failure to include the file might prevent devices from successfully starting from the installation media and can result in error code 0xc0430001.
Note
The boot.stl file is used during Secure Boot validation and must match the Windows version and architecture of the image you are updating.
To ensure the boot.stl file is included as part of the installation media, do one of the following:
- Use the Update WinPE script to update an existing Windows image. (Recommended)
- Manually copy the boot.stl file from the device Windows\Boot\EFI folder to the corresponding folder on your installation media before deploying the update.
For information about how to apply Dynamic Update packages to existing Windows images, see Update Windows installation media with Dynamic Update.
Install this update
To install this update, use one of the following Windows and Microsoft release channels.
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This update downloads and installs automatically from Windows Update and Microsoft Update. |
File information
For a list of the files provided in this update, download the file information for cumulative update KB5127648.
For a list of the files provided in the servicing stack update, download the file information for the SSU KB5127647 - (Build 26100.9703).
Related topics
Windows monthly updates explained
Description of the standard terminology used for Microsoft software updates
Microsoft Store for Business and Education with Configuration Manager