Microsoft Support:
April 19, 2026 - Hotpatch KB5091470 (OS Build 26100.32704) Out-of-band
Applies To: Windows Server 2025 Datacenter: Azure EditionThis out-of-band (OOB) update for Windows Server 2025 (KB5091470) is a non-security cumulative update.
To view the latest updates about this release, visit the Windows release health dashboard or the update history page for Windows Server 2025.
Note: Windows Server 2025 Datacenter & Standard machines connected to Azure Arc, now have the option to subscribe to Hotpatch servicing. Hotpatch provides the ability to install OS security updates without restarting your machine.
Improvements and fixes
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.- [Domain controllers (known issue)] Fixed: After installing the April 14, 2026, (KB5082063) Windows security update 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.
Note: The update is only offered to devices that already installed KB5082063.
If you've already installed previous updates, your device will download and install only the new updates included in this package.
Known issues in this update
1 Windows Server Update Services (WSUS) does not display error details
After installing KB5070893 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 updateMicrosoft now combines the latest servicing stack update (SSU) for your operating system with the Hotpatch update. For general information about SSUs, see Servicing stack updates.
If you are using Windows Update, the latest SSU installs with this 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. |
| See the other options. |
File information
For a list of the files provided in this update, download the file information for cumulative update 5091470.
For a list of the files provided in the servicing stack update, download the file information for the SSU (KB5082062) - version 26100.32692.
Source:
April 19, 2026—Hotpatch KB5091470 (OS Build 26100.32704) Out-of-band - Microsoft Support
support.microsoft.com
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