Microsoft offers temporary solution for malfunctioning Windows Server 2022 virtual machines.

Microsoft has recognized a critical issue that leads to blue screen errors and prevents Windows Server 2022 virtual machines (VMs) from booting on VMware ESXi hosts, specifically after the KB5031364 October 2023 cumulative update installation.

Reports from administrators indicated VMs failing to start [1, 2, 3, 4, 5] following the update installation during the last Patch Tuesday. Microsoft has now confirmed these problems, clarifying that they affect VMware ESXi hosts updated last month.

The company detailed that impacted VMs will encounter a blue screen error with the Stop code: PNP DETECTED FATAL ERROR. This issue is isolated to VMs on VMware ESXi hosts that meet the following criteria:

- Utilize AMD Epyc physical processors.
- Have "Expose IOMMU to guest OS" enabled in the VMware VM settings.
- Feature "Enable Virtualization Based Security" turned on in Windows Server 2022.
- Have "System Guard Secure Launch" activated in Windows Server 2022.

Microsoft is actively working on a resolution, with an anticipated fix expected to be available next week.

In the meantime, administrators can temporarily bypass this issue by disabling the "Expose IOMMU to guest OS" option in the VM settings, although this workaround may not be feasible in all environments due to specific system requirements.

Another potential solution involves uninstalling the KB5031364 update, which, while it does address the boot issue, also removes the security patches included in the update. To uninstall, use the Windows Update Standalone Installer (WUSA) via an elevated command prompt by following these steps:

1. Open the Start menu and type 'cmd'.
2. Right-click the Command Prompt application and select 'Run as Administrator'.
3. Execute the following command:
   

   wusa /uninstall /kb:5031364

Previously, Microsoft released urgent fixes for similar issues affecting Hyper-V VMs, addressing boot failures and issues with creating new VMs on certain Hyper-V hosts in January and December 2022.

Earlier this year, a related problem was confirmed that affected VMware ESXi VMs with Secure Boot after installing February 2023 cumulative updates. VMware quickly followed with vSphere ESXi updates to resolve the underlying cause, which prevented VMs from detecting a bootable operating system.