Microsoft has released emergency out-of-band (OOB) Windows Server updates to address a known issue with creating virtual machines (VMs) on Hyper-V hosts after installing this month’s Patch Tuesday updates -this.

The issue only affects virtual machines managed with System Center Virtual Machine Manager (SCVMM) and using software-defined networking (SDN).

On affected systems, Windows administrators see warnings during live migration, SLB load balancer or RAS SDN gateway fails, and experience failures when creating new VMs and connecting interface cards virtual network (VNIC).

Only Windows Server 2019 and Windows Server 2022 are expected to be impacted after installing the December 2022 Patch Tuesday updates (KB5021237 and KB5021249).

To resolve this issue, administrators should install the cumulative OOB updates released today for their systems on all affected Hyper-V hosts in their environment.

“You do not need to install any updates or make changes to other servers or client devices in your environment to resolve this issue,” Microsoft said. said tuesday.

OOB updates not provided through Windows Update

Today’s updates are not delivered through Windows Updates and will not automatically install on affected servers.

To get the standalone package, you will need to find the KB number in the Microsoft Update Catalogdownload and install them manually.

They can also be manually imported into Windows Server Update Services (WSUS) and Microsoft Endpoint Configuration Manager.

Microsoft also provides instructions for importing updates into WSUS and Control Panel from the Microsoft Update Catalog.

The list of Windows Server Emergency Cumulative Updates released today includes:

“You do not need to apply a previous update before installing these cumulative updates,” Redmond added today.

“If you have already installed the updates released on December 13, 2022, you do not need to uninstall the affected updates before installing subsequent updates, including the updates listed above. “

A temporary solution is also available for administrators who cannot immediately install today’s updates on affected SDN-based SCVMM deployments.

This workaround requires running a set of commands on all Hyper-V hosts managed by SCVMM from an elevated PowerShell window (immediately after installing updates KB5021237 and KB5021249).

You can find scripts for large scale deployments on the SCVMM management server and more details on applying the workaround in this support article.