After installing this month’s Patch Tuesday updates, Microsoft has released emergency out-of-band (OOB) Windows Server updates to address a known issue breaking virtual machine (VM) creation on Hyper-V hosts. The issue only affects VMs managed with the System Center Virtual Machine Manager (SCVMM) and using Software Defined Networking (SDN). On affected systems, Windows admins see warnings during live migration, SLB Load Balancer or SDN RAS Gateway fails, and experience failures when creating new VMs and attaching Virtual Network Interface Cards (VNICs). Only Windows Server 2019 and Windows Server 2022 should be impacted after installing December 2022 Patch Tuesday updates (KB5021237 and KB5021249).
To resolve this issue, admins must install the OOB cumulative updates released on December 20, 2022 on all affected Hyper-V hosts in their environment. “You do not need to install any update or make any changes to other servers or client devices in your environment to resolve this issue,” Microsoft said on Tuesday.