Important
Free support for Windows 10 Enterprise LTSC 2021 will end soon. For information about the availability of an Extended Security Update (ESU), see the End of support section.
Summary
This article lists the security issues and quality improvements included in this cumulative security update.
Applies to: Windows 10 ESU
Important
Use EKB KB5015684 to update to Windows 10, version 22H2.
This security update includes fixes and quality improvements that are part of the following updates:
The following is a summary of the issues that this update addresses when you install this update. If there are new features, it lists them as well. The bold text within the brackets indicates the item or area of the change we are documenting.
[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.
[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.
[OMA DM protocol] This update improves the logging features of the OMA DM Client (omadmclient.exe) component. More debug information is now saved when connecting to a server.
[Windows Code Integrity policies] Improves application compatibility during Windows certificate-authority rotation by recognizing Microsoft Windows Production PCA 2026 RSA2048-SHA256 as equivalent to PCA 2011.
[Remote Desktop] This update addresses an issue that affects Remote Desktop audio redirection. Audio from the remote session might not play on the local computer in certain configurations.
[BitLocker Group Policy] This update addresses the "Devices with an unrecommended BitLocker Group Policy configuration might be required to enter their BitLocker recovery key" known issue.
If you installed earlier updates, only the new updates contained in this package will be downloaded and installed on your device.
For more information about security vulnerabilities, please refer to the new Security Update Guide website and the September 2026 Security Updates.
For information about Windows update terminology, see the article about the types of Windows updates and the monthly quality update types. For an overview of Windows 10, version 22H2, see its update history page.
Known issues in this update
USB Audio Class 1.0 devices with error Code 10 or no output
Symptoms
After installing the September 8, 2026, Windows security update, 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. 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.
Remote Desktop Services might stop responding after September 2026 security update
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.
Resolution
This issue is resolved in Windows updates released on and after September 14, 2026 such as KB5129236. We recommend you install the latest Windows update for your device as it contains important improvements and issue resolutions, including this one.
File History might stop working after installing September 2026 Windows update
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 October 13, 2026 such as KB5126657. We recommend you install the latest Windows update for your device as it contains important improvements and issue resolutions, including this one.
| Available | Next Step |
|---|---|
|
This update will be downloaded and installed automatically from Windows Update. |
File information
A list of the files that are included in this update are provided in a CSV (Comma delimited) (*.csv) file. The file can be opened in a text editor such as Notepad or in Microsoft Excel.
Note The English (United States) version of this software update might contain files for additional languages.
Download the file information for cumulative update KB5122878.
Download the file information for update SSU (KB5122877) - version 19041.7714.
Related topics
Microsoft Store application updates
Windows updates do not install Microsoft Store application updates. If you are an enterprise user, see Microsoft Store apps - Configuration Manager. If you are a consumer user, see Get updates for apps and games in Microsoft Store.Windows Secure Boot certificate expiration
Important: Secure Boot certificates used by most Windows devices have started expiring in June 2026. This might affect the ability of certain personal and business devices to boot securely if not updated in time. To avoid disruption, we recommend reviewing the guidance and taking action to update certificates in advance. For details and preparation steps, see Windows Secure Boot certificate expiration and CA updates.
- End of support
Microsoft will no longer provide free software updates from Windows Update, technical assistance, or security fixes on the following end dates. To continue to receive critical and important security updates for Windows 10, see Windows 10 Extended Security Updates (ESU). Otherwise, we recommend you upgrade to a later version of Windows.- Windows 10, version 21H2: Support ended on June 13, 2023
- Windows 10, version 22H2: Support ended on October 14, 2025
- Extended Security Updates (ESU) program for Windows 10
- Windows 10 Enterprise LTSC 2021: January 12, 2027. For information about the Extended Security Updates (ESU) program, see Plan for Windows 10 Enterprise LTSC 2021 end of support
- Windows 10 IoT Enterprise LTSC 2021: January 13, 2032
Change log
| Change date | Description |
|---|---|
| October 10, 2026 | Updated known issue "USB Audio Class 1.0 devices with error Code 10 or no output". |
| September 19, 2026 | Added a known issue, "File History might stop working after installing September 2026 Windows update". |
| September 14, 2026 | Added the resolution for the known issue "Remote Desktop Services might stop responding after September 2026 security update". |
| September 12, 2026 | Added a known issue, "Remote Desktop Services might stop responding after September 2026 security update". |
| September 8, 2026 | Known issue updated: "Devices with an unrecommended BitLocker Group Policy configuration might be required to enter their BitLocker recovery key". For more information, see a Windows update released on or after April 14, 2026 such as KB5082200. |