April 19, 2026—KB5091157 (OS Build 26100.32698) Out-of-band
Applies To
Release Date:
19/4/2026
Version:
OS Build 26100.32698
This out-of-band (OOB) update for Windows Server 2025 (KB5091157) is a non-security cumulative update.
Improvements
This out-of-band update contains quality improvements from KB5082063 (released April 14, 2026). The following summary outlines key issues addressed by this out-of-band update. The bold text within the brackets indicates the item or area of the change.
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[Domain controllers (known issue)] Fixed: After installing the April 14, 2026, Windows security update (KB5082063) and restarting, domain controllers with multi-domain forests that use Privileged Access Management (PAM), might experience startup issues. In some cases, Local Security Authority Subsystem Service (LSASS) might stop responding, leading to repeated restarts, and preventing authentication and directory services, which can make the domain unavailable.
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[Windows update installation] Fixed: A small number of Windows Server 2025 devices might fail to install the April 14, 2026, Windows security update (KB5082063). When this issue occurs, affected devices might display one of the following error messages: “Install error: 0x800F0983” or “Some update files are missing or have problems. We’ll try to download the update again later. Error code: 0x80073712.”
If you installed earlier updates, your device downloads and installs only the new updates contained in this package.
Note Hotpatch update-enrolled Windows Server 2025 devices affected by the KB5082063 installation issue can install this OOB update for the same protections. However, doing so will require a restart, and hotpatch updates will not resume until the July 2026 baseline update.
Windows Sever 2025 servicing stack update (KB5082062) -26100.32692
This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. Servicing stack updates (SSU) ensure that you have a robust and reliable servicing stack so that your devices can receive and install Microsoft updates. To learn more about SSUs, see Simplifying on-premises deployment of servicing stack updates.
Known issues in this update
Symptom
Some devices with an unrecommended BitLocker Group Policy configuration might be required to enter their BitLocker recovery key on the first restart after installing this update.
This issue only affects a limited number of systems in which ALL of the following conditions are true. These conditions are unlikely to be found on personal devices not managed by IT departments.
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BitLocker is enabled on the OS drive.
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The Group Policy "Configure TPM platform validation profile for native UEFI firmware configurations" is configured, and PCR7 is included in the validation profile (or the equivalent registry key is set manually).
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System Information (msinfo32.exe) reports Secure Boot State PCR7 Binding as "Not Possible".
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The Windows UEFI CA 2023 certificate is present in the device’s Secure Boot Signature Database (DB), making the device eligible for the 2023‑signed Windows Boot Manager to be made the default.
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The device is not already running the 2023-signed Windows Boot Manager.
In this scenario, the BitLocker recovery key only needs to be entered once -- subsequent restarts will not trigger a BitLocker recovery screen, as long as the group policy configuration remains unchanged. For help finding your BitLocker recovery key, see the article, Find your BitLocker recovery key.
Enterprises are recommended to audit their BitLocker group policies for explicit PCR7 inclusion and check msinfo32.exe for their PCR7 binding status before installing this update. (See Option 1 below.)
Workaround
Option 1: Remove the Group Policy configuration before installing the update (Recommended)
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Open Group Policy Editor (gpedit.msc) or your Group Policy Management Console.
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Navigate to: Computer Configuration > Administrative Templates > Windows Components > BitLocker Drive Encryption > Operating System Drives.
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Set "Configure TPM platform validation profile for native UEFI firmware configurations" to "Not Configured".
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Run the following command on affected devices to propagate the policy change: gpupdate /force
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Run the following command to suspend BitLocker (where BitLocker is enabled on the C: drive): manage-bde -protectors -disable C:
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Run the following command to resume BitLocker (where BitLocker is enabled on the C: drive): manage-bde -protectors -enable C:
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This updates the BitLocker bindings to use the Windows-selected default PCR profile.
Option 2: Apply the Known Issue Rollback (KIR) before installing the update
A Known Issue Rollback (KIR) is available for customers who cannot remove the PCR7 group policy before deploying this update. The KIR prevents the automatic switch to the 2023 Boot Manager, avoiding the BitLocker recovery trigger. The KIR should be deployed before installing the update on affected devices. Contact Microsoft’s Support for business to obtain this KIR.
A permanent resolution for this issue is planned in a future Windows update. More information will be provided when it is available.
After installing KB5070881 or later updates, Windows Server Update Services (WSUS) does not display synchronization error details within its error reporting. This functionality is temporarily removed to address the Remote Code Execution Vulnerability, CVE-2025-59287.
How to get this update
Before you install this update
Microsoft now 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.
Install this update
To install this update, use one of the following Windows and Microsoft release channels.
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To install this release from the Microsoft Update Catalog, follow these instructions: Before you install this update, the standalone package(s) for this update, go to the Microsoft Update Catalog website. This KB contains one or more MSU files that require installation in a specific order. You can install this update using Method 1 (install all MSU files together) or Method 2 (install each MSU file individually, in order). Method 1: Install all MSU files together Download all MSU files for KB5091157 from Microsoft Update Catalog and place them in the same folder (for example, C:/Packages). Use Deployment Image Servicing and Management (DISM.exe) to install the target update. DISM will use the folder specified in PackagePath to discover and install one or more prerequisite MSU files as needed. Updating Windows PC To apply this update to a running Windows PC, run the following command from an elevated Command Prompt:
Or, run the following command from an elevated Windows PowerShell prompt:
Or use Windows Update Standalone Installer to install the target update. Updating Windows Installation media To apply this update to Windows Installation media, see Update Windows installation media with Dynamic Update. Note: When downloading other Dynamic Update packages, ensure they match the same month as this KB. If the SafeOS Dynamic Update or Setup Dynamic Update is not available for the same month as this KB, use the most recently published version of each. To add this update to a mounted image, run the following command from an elevated Command Prompt:
Or, run the following command from an elevated Windows PowerShell prompt:
Method 2: Install each MSU file individually, in order Download and install each MSU file individually either using DISM or Windows Update Standalone Installer in the following order:
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If you want to remove this update
Caution: Before you decide to remove this update, see Understanding the risks: Why you should not uninstall security updates.
To remove this update after installing the combined SSU and LCU package, use the DISM/Remove-Package command line option with the LCU package name as the argument. You can find the package name by using this command: DISM /online /get-packages.
Running Windows Update Standalone Installer (wusa.exe) with the /uninstall switch on the combined package will not work because the combined package contains the SSU. You cannot remove the SSU from the system after installation.
File Information
For a list of the files provided in this update, download the file information for out-of-band update 5091157.
For a list of the files provided in the servicing stack update, download the file information for SSU (KB5082062) - version 26100.32692.
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