November 10, 2026—KB5131085 (OS Build 17763.9487)

Applies To
Windows Server 2019 Win 10 Ent LTSC 2019

Summary

This article lists the security issues and quality improvements included in this cumulative security update.

Applies to: Windows Server 2019

This security update includes fixes and quality improvements that are part of the following update:

The following is a summary of the issues that this update addresses when you install this update. The bold text within the brackets indicates the item or area of the change we are documenting.

  • [Date and Time] This update adjusts daylight saving time (DST) rules for Cuba for the extended 2026-2027 DST period. Cuba remains on UTC-04:00 and doesn't observe the November 2026 and March 2027 transitions. It returns to UTC-05:00 in November 2027 and resumes its regular seasonal schedule in 2028.

  • [Printing] - Fixed: Adding a printer published in Active Directory through Settings > Bluetooth & devices > Printers & scanners > Add device might fail with error 87, "The parameter is incorrect." This issue was introduced by the October 2026 update and does not generally affect existing printers or printing.

  • [Windows Deployment Services] Fixed: After installing this security update, the Import-WdsInstallImage cmdlet requires administrator privileges. Attempts to run the cmdlet as a non-administrator fail with an ACCESS_DENIED error.

  • [Remote Desktop Web Access] Fixed: RD Web Access might fail to load and display “Unable to display RD Web Access” in Microsoft Edge or Google Chrome when XSLT is disabled by browser policy. RD Web Access pages are now rendered on the server and no longer depend on browser XSLT support. To learn more, see KB5130994: RD Web Access fails to load when XSLT is disabled in Microsoft Edge or Google Chrome.

  • [Remote Desktop]

    • Fixed: The “Specify thumbprints of certificates representing trusted .rdp publishers” policy could not be configured successfully through Microsoft Intune.
    • Fixed: Remote Desktop shadow connections might fail with an “Unspecified error” on Windows Server 2016 and Windows Server 2012 R2 after installing the October 14, 2026, update.

  • [Exchange Server] This update fixes an issue that affects on-premises Exchange servers. The issue might prevent signing in to Outlook on the web (OWA), cause email messages to remain in the Outlook Outbox without being delivered, or prevent Exchange from accessing mailboxes during mailbox replication.

  • [Windows PowerShell] This update strengthens security for PowerShell script signing and signature verification by introducing stricter encoding validation. As a result, scripts containing invalid UTF-8 encoding might fail signature validation, even if they were previously accepted. To resolve this issue, review the affected scripts, save them using valid UTF-8 encoding with a byte order mark (BOM), and sign them again. For further guidance, see Encoding Guidance for Signed PowerShell Scripts.

Known issues in this update

Users might be unable to sign in to OWA or send emails on Exchange Server

Symptoms:

After installing this update, some on-premises Exchange servers might experience issues accessing or sending email. Users might be unable to sign in to Outlook on the web (OWA), or email messages sent from Outlook might remain in the Outbox and not be delivered. Additionally, Exchange might experience issues accessing mailboxes during mailbox replication.

In some affected configurations, Exchange Server OWA might fail with an error MapiExceptionMdbOffline: Unable to make connection to the server. (hr=0x80004005, ec=1142) with Event ID 1006 logged in the application log. Another reported symptom is growing email queues. Installing the October 2026 Exchange server security updates isn’t required for these issues to occur.

Workaround

This issue can be temporarily mitigated by modifying the registry key as described in Exchange servers may become unstable after installation of October 2026 Windows updates.

The October 2026 update introduced a default limit on the amount of memory used by Endpoint Mapper when handling Endpoint Lookup calls.

For workloads such as Exchange Server, the default limit of 512 simultaneous Endpoint Lookup calls might not be sufficient under heavy load. Administrators can use this registry setting to increase the maximum number of simultaneous Endpoint Lookup calls, which increases the amount of memory that Endpoint Mapper can use.

Microsoft Support: An additional mitigation is available for affected devices through Microsoft Support. To apply this mitigation in your organization, please contact Microsoft Support for business.

Next steps: Microsoft investigating this issue and will provide more information when it is available.

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.

Servicing stack update (KB5131084) - 17763.9478

Microsoft now combines the latest servicing stack update (SSU) for your operating system with the latest cumulative update (LCU). SSUs improves the reliability of the update process and includes fixes to the servicing stack, the component that installs Windows updates.

This servicing stack update (SSU) includes enhanced logic to verify whether a device is hosted on Azure, leveraging an updated certificate chain for validation. To ensure that the device can access the required certificate update domains to successfully download and install certificate updates, see Certificate downloads and revocation lists and Azure Certificate Authority details. To learn more about SSUs, see Servicing stack updates.

How to get this update

Before you install this update

  • For Windows Update: You must have the Windows update released on or after July 8, 2025 (such as KB5062557) installed before installing this update.

  • For Windows Server Update Services (WSUS) deployment or when installing the standalone package from Microsoft Update Catalog: You must have the Windows update released on or after July 8, 2025 (such as KB5062557) installed before installing this update.

  • Servicing Stack Update (SSU): You must have installed servicing stack update version 17763.7557 or later before installing this update. To determine the latest SSU installed on your device, run DISM /Online /Get-Packages | findstr /i "ServicingStack" from an elevated command prompt. The Package Identity line returned must be version 17763.7557 or later.

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.

Get and install this update

To get and install this update, use one of the following Windows or Microsoft release channels.

Available Next Step
Available 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 Download the file information for cumulative update KB5131085.

Download Download the file information for SSU (KB5131084) - version 17763.9478.

References

  • 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.

  • 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.

  • End of support

    Microsoft will no longer provide free software updates from Windows Update, technical assistance, or security fixes on the following end dates. We recommend that you upgrade to a later version of Windows Server.