UPDATE 9/22:
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Windows Secure Boot certificate expiration
Important
Secure Boot certificates used by most Windows devices started to expire on June 2026. Microsoft has been updating these certificates on PCs and non-managed business devices for the past months. Devices that haven't received the newer certificates will continue to start, and standard Windows updates will continue to install. We will continue to install the newer certificates via Windows updates in the coming months.
End of updates
Windows 11, version 24H2 Home and Pro editions will reach end of updates on October 13, 2026. Devices running these editions will no longer receive fixes for known issues, time zone updates, technical support, or monthly security and preview updates containing protections from the latest security threats. Enterprise and Education editions remain supported until October 12, 2027.
To stay protected and up to date, we recommend you upgrade to the latest version of Windows 11.
Change log
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.
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.
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Servicing stack update
Includes KB5124007 (Build 26100.9441), which improves the reliability of the Windows update installation process. To learn more about SSUs, see Simplifying on-premises deployment of servicing stack updates.
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:
For a list of the files provided in the servicing stack update, download the file information for the SSU (KB5124007) - version 26100.9441.
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KB5124010 Windows 11 Cumulative Update Preview build 26100.9550 (24H2), 26200.9550 (25H2), and 26300.9550 (26H2) - Sept. 22
UPDATE 10/13: https://www.elevenforum.com/t/kb5127648-windows-11-cumulative-update-build-26100-9711-24h2-26200-9711-25h2-26300-9711-26h2-oct-13.50115/ Microsoft Support: This cumulative update for Windows 11, versions 26H2, 25H2, and 24H2 (KB5124010), includes production-quality improvements...
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Microsoft Support:
Announcements and messages
This section provides key notifications related to this release, including announcements, change logs, and end-of-support notices.Windows Secure Boot certificate expiration
Important
Secure Boot certificates used by most Windows devices started to expire on June 2026. Microsoft has been updating these certificates on PCs and non-managed business devices for the past months. Devices that haven't received the newer certificates will continue to start, and standard Windows updates will continue to install. We will continue to install the newer certificates via Windows updates in the coming months.
End of updates
Windows 11, version 24H2 Home and Pro editions will reach end of updates on October 13, 2026. Devices running these editions will no longer receive fixes for known issues, time zone updates, technical support, or monthly security and preview updates containing protections from the latest security threats. Enterprise and Education editions remain supported until October 12, 2027.
To stay protected and up to date, we recommend you upgrade to the latest version of Windows 11.
Change log
Change date | Change description |
|---|---|
| September 18, 2026 | Added a known issue, "File History might stop working after installing September 2026 Windows update". |
| September 18, 2026 | Added a known issue, "Domain-joined devices might lose their secure trust relationship with the domain". |
| September 12, 2026 | Added a known issue, "USB audio devices might fail to start or produce no sound". |
| September 11, 2026 | Added a known issue, "Remote Desktop Services might stop responding after September 2026 security update". |
| September 11, 2026 | Added a known issue, "Host folder shares might be unavailable in Hyper-V-based Linux VMs". |
Improvements
This update includes improvements from the following previously released updates: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 includes additional high confidence device targeting data, increasing coverage of devices eligible to automatically receive new Secure Boot certificates. Certificate deployment via Windows updates continues across supported PCs and non-managed business devices in the coming months.
- [Mouse] Fixed: This update addresses an issue that prevented customized mouse cursor settings, including pointer style and color, from displaying correctly. Selected cursor options and colors now work as expected.
- [Personalization] Fixed: This update addresses an issue where desktop background and other personalization settings might not load correctly, causing the desktop background to appear black.
- [Teams and Outlook on Arm64 PCs] Fixed: This update addresses an issue that could cause Microsoft Teams and Microsoft Outlook to unexpectedly close on Arm64-based PCs.
- [Date and Time] This update adjusts Morocco Standard Time to reflect Morocco's transition to permanent UTC+00:00 effective September 20, 2026. This change ensures that the correct local time is displayed after the transition.
- [Remote Desktop Audio Redirection] This update addresses an issue affecting Remote Desktop audio redirection that could prevent audio from a remote session from playing on the local device in certain configurations.
- [OMA-DM Client Logging] This update improves diagnostic logging for the OMA-DM client, providing additional information to help troubleshoot device management server connection issues.
Components updates
AI componentsThis 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.
View AI Components Installed on Windows 11 PC
This tutorial will show you how to view all AI components installed on your Windows 11 PC. If your Windows 11 device (ex: Copilot+ PC) has a NPU, you will have a System > AI components page in Settings. AI components are used on Copilot+ PCs and enable AI models to run locally, directly on the...
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Servicing stack update
Includes KB5124007 (Build 26100.9441), which improves the reliability of the Windows update installation process. To learn more about SSUs, see Simplifying on-premises deployment of servicing stack updates.
Known issues in this update
Symptoms
After installing the August 2026 Windows non-security preview update KB5120998 and subsequent updates, some devices might experience desktop loading issues. This issue has been primarily observed on Azure Virtual Desktop (AVD) hosts using FSLogix. This issue appears to occur more frequently with some existing user profiles.
Affected users might see a black screen after sign-in, with the desktop session failing to load automatically. In some cases, users might be unable to access their desktop until the desktop session is started manually. Application event logs might also show Windows Explorer crashes.
Resolution
This issue is resolved in Windows updates released on and after October 13, 2026 such as KB5127648. We recommend you install the latest Windows update for your device as it contains important improvements and issue resolutions, including this one.
After installing the August 2026 Windows non-security preview update KB5120998 and subsequent updates, some devices might experience desktop loading issues. This issue has been primarily observed on Azure Virtual Desktop (AVD) hosts using FSLogix. This issue appears to occur more frequently with some existing user profiles.
Affected users might see a black screen after sign-in, with the desktop session failing to load automatically. In some cases, users might be unable to access their desktop until the desktop session is started manually. Application event logs might also show Windows Explorer crashes.
Resolution
This issue is resolved in Windows updates released on and after October 13, 2026 such as KB5127648. We recommend you install the latest Windows update for your device as it contains important improvements and issue resolutions, including this one.
Symptoms
After installing the September 8, 2026, Windows security update (KB5124008), or later updates, some Credential Guard protected machine accounts might lose their secure channel with an on-premises Active Directory (AD) domain. Users might then be unable to sign in interactively with valid domain credentials and might receive a message stating that the trust relationship between the device and the domain failed. Offline sign-in using previously cached credentials might continue to work. AD replication and AD services on the domain controllers are not affected.
This issue occurs because KB5124008 and later updates enable the Machine Identity Isolation feature. While the update does not directly enable Machine Identity Isolation enforcement, it does cause Windows to begin honoring any existing or policy-provisioned settings that enabled Machine Identity Isolation enforcement. However, this feature is only supported for environments connected to domain controllers running at a Windows Server 2025 Domain Functional Level (DFL) and above. The feature should be disabled elsewhere. Any devices previously configured to use Machine Identity Isolation that are not connected to Windows Server 2025 domain controllers will experience this issue and will need to disable the feature.
Resolution
This issue is addressed by KB5124010. This update prevents Machine Identity Isolation (MII) enforcement by disabling it completely while improvements are made to the feature. MII enforcement will be prevented regardless of the MII configuration.
After installing the September 8, 2026, Windows security update (KB5124008), or later updates, some Credential Guard protected machine accounts might lose their secure channel with an on-premises Active Directory (AD) domain. Users might then be unable to sign in interactively with valid domain credentials and might receive a message stating that the trust relationship between the device and the domain failed. Offline sign-in using previously cached credentials might continue to work. AD replication and AD services on the domain controllers are not affected.
This issue occurs because KB5124008 and later updates enable the Machine Identity Isolation feature. While the update does not directly enable Machine Identity Isolation enforcement, it does cause Windows to begin honoring any existing or policy-provisioned settings that enabled Machine Identity Isolation enforcement. However, this feature is only supported for environments connected to domain controllers running at a Windows Server 2025 Domain Functional Level (DFL) and above. The feature should be disabled elsewhere. Any devices previously configured to use Machine Identity Isolation that are not connected to Windows Server 2025 domain controllers will experience this issue and will need to disable the feature.
Resolution
This issue is addressed by KB5124010. This update prevents Machine Identity Isolation (MII) enforcement by disabling it completely while improvements are made to the feature. MII enforcement will be prevented regardless of the MII configuration.
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:
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.
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.
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.
Symptoms
After installing the September 2026 security update (KB5124008), applications that use HCS-managed virtual machines might experience issues when sharing host folder with Linux VMs using Plan9. Affected virtual machines start normally, but folders shared from the Windows host using Plan9 do not appear or cannot be accessed in the guest environment.
Applications or sandbox environments that depend on these shared folders might display an error indicating that no Plan9 drive shares were mounted. Claude Cowork and the Windows Subsystem for Linux (WSL) are two of the applications affected by this issue. Standard Hyper-V virtual machines that do not use the Plan9 feature are not affected by this issue.
Resolutions
This issue is resolved in Windows updates released on and after September 14, 2026 such as KB5129195.
After installing the September 2026 security update (KB5124008), applications that use HCS-managed virtual machines might experience issues when sharing host folder with Linux VMs using Plan9. Affected virtual machines start normally, but folders shared from the Windows host using Plan9 do not appear or cannot be accessed in the guest environment.
Applications or sandbox environments that depend on these shared folders might display an error indicating that no Plan9 drive shares were mounted. Claude Cowork and the Windows Subsystem for Linux (WSL) are two of the applications affected by this issue. Standard Hyper-V virtual machines that do not use the Plan9 feature are not affected by this issue.
Resolutions
This issue is resolved in Windows updates released on and after September 14, 2026 such as KB5129195.
Symptoms
After installing the September 2026 Windows security update, some organizations might experience issues with Remote Desktop Services (RDS).
In some environments, RDS might become unstable, resulting in RDP connections failing after several minutes, sign-in issues, or servers hanging at "Please wait for the Remote Desktop Configuration". Related tools, including Microsoft Management Console (MMC), RDS Licensing Diagnoser, and File Explorer might also become unresponsive. Additionally, the Windows Update page might stop responding and continuously display a loading indicator.
Note: This issue does not affect Windows 365 or Azure Virtual Desktop.
Microsoft Support: IT administrators who need an immediate workaround should contact Microsoft Support for Business for assistance.
Resolution
This issue is resolved in Windows updates released on and after September 14, 2026 such as KB5129195. We recommend you install the latest Windows update for your device as it contains important improvements and issue resolutions, including this one.
After installing the September 2026 Windows security update, some organizations might experience issues with Remote Desktop Services (RDS).
In some environments, RDS might become unstable, resulting in RDP connections failing after several minutes, sign-in issues, or servers hanging at "Please wait for the Remote Desktop Configuration". Related tools, including Microsoft Management Console (MMC), RDS Licensing Diagnoser, and File Explorer might also become unresponsive. Additionally, the Windows Update page might stop responding and continuously display a loading indicator.
Note: This issue does not affect Windows 365 or Azure Virtual Desktop.
Microsoft Support: IT administrators who need an immediate workaround should contact Microsoft Support for Business for assistance.
Resolution
This issue is resolved in Windows updates released on and after September 14, 2026 such as KB5129195. We recommend you install the latest Windows update for your device as it contains important improvements and issue resolutions, including this one.
Symptoms
After installing the September 2026 Windows security update KB5124008, some customers using File History, might be unable to create or update backups. File History, available through Control Panel > System and Security > File History, is used to back up files to an external drive or network location. Affected devices might incorrectly display a "Reconnect your drive" message even when a compatible backup drive is connected and functioning properly. Additionally, the "Last Backup" timestamp might not update, and previously backed up files might show "No previous version available." In some cases, Event Viewer might record application crash events referencing FileHistory.exe and KERNELBASE.dll.
Resolution
This issue is resolved in Windows updates released on and after September 22, 2026 such as KB5124010. We recommend you install the latest Windows update for your device as it contains important improvements and issue resolutions, including this one.
After installing the September 2026 Windows security update KB5124008, some customers using File History, might be unable to create or update backups. File History, available through Control Panel > System and Security > File History, is used to back up files to an external drive or network location. Affected devices might incorrectly display a "Reconnect your drive" message even when a compatible backup drive is connected and functioning properly. Additionally, the "Last Backup" timestamp might not update, and previously backed up files might show "No previous version available." In some cases, Event Viewer might record application crash events referencing FileHistory.exe and KERNELBASE.dll.
Resolution
This issue is resolved in Windows updates released on and after September 22, 2026 such as KB5124010. We recommend you install the latest Windows update for your device as it contains important improvements and issue resolutions, including this one.
How to get this update
Before you install this update
Microsoft combines the latest servicing stack update (SSU) for your operating system with the latest cumulative update (LCU). For general information about SSUs, see Servicing stack updates.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.
Install this update
To install this update, use one of the following Windows and Microsoft release channels.| Available | Next Step |
|---|---|
| This update downloads and installs automatically from Windows Update and Microsoft Update. |
|
| To install this release from the Microsoft Update Catalog, select the option that matches your device architecture (Arm64 or x64), and then follow the instructions. Note: This latest cumulative update includes updates for AI components. Even though the AI component updates are included in the update, the AI components are only applicable to Windows Copilot+ PCs and will not install on Windows PC or Windows Server. |
File information
For a list of the files provided in this update, download the file information for cumulative update KB5124008.For a list of the files provided in the servicing stack update, download the file information for the SSU (KB5124007) - version 26100.9441.
Source:
September 8, 2026—KB5124008 (OS Builds 26200.9445 and 26100.9445) | Microsoft Support
September 8, 2026—KB5124008 (OS Builds 26200.9445 and 26100.9445)
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Download Official Windows 11 ISO file from Microsoft
This tutorial will show you how to download an official Windows Server or Windows 11 64-bit or ARM64 ISO file from Microsoft. Microsoft provides ISO files for Windows Server and Windows 11 to download. You can use these ISO files to clean install or in-place upgrade Windows 11. The Flight Hub...
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UUP Dump - Download Windows Insider ISO
UUP Dump is the most practical and easy way to get ISO images of any Insider Windows 10 or Windows 11 version, as soon as Microsoft has released a new build. UUP Dump creates a download configuration file according to your choices, downloads necessary files directly from Microsoft servers, and...
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