KB5091157: [Windows update installation] Fixed

April 19, 2026—KB5091157 (OS Build 26100.32698) Out-of-band

​​​​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.

• [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.
• [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.