Product reviews, deals and the latest tech news

Microsoft Resolves Windows Server VM Issues Caused by October Updates

Microsoft has resolved a known issue that was causing blue screens and boot failures in Windows Server 2022 virtual machines (VMs) deployed on VMware ESXi hosts. Administrators began reporting VM start issues after installing the KB5031364 cumulative update released last month.

The problem specifically affected guest VMs on VMware ESXi hosts with AMD Epyc physical processors. The issue was triggered when the “Expose IOMMU to guest OS” option in VMware was enabled alongside Virtualization-Based Security and System Guard Secure Launch in Windows Server 2022. Microsoft acknowledged the problem shortly after reports surfaced and confirmed that it impacted these specific configurations.

The root cause has now been addressed with the KB5032198 Windows Server 2022 cumulative update, released as part of this month’s Patch Tuesday. According to Microsoft, “This update addresses a known issue that affects virtual machines (VMs) that run on VMware ESXi hosts. Windows Server 2022 might fail to start up. The affected VMs will receive an error with a blue screen and a stop code: PNP DETECTED FATAL ERROR.”

For administrators unable to install the November 2023 Patch Tuesday updates immediately, there are temporary workarounds available. One involves disabling the “Expose IOMMU to guest OS” option in the VM settings. However, this solution might not be suitable for all environments, as some systems require this option to be enabled by default. Another workaround is to uninstall the problematic KB5031364 update, though this also removes all security patches included in the update.

This is not the first time Microsoft has had to release updates to address VM boot issues. In January and December 2022, out-of-band updates were issued to fix problems blocking Hyper-V VMs from booting and creating new VMs on specific hosts. Earlier this year, a similar issue affected VMware ESXi VMs with Secure Boot enabled after the February 2023 cumulative updates were installed. VMware responded by releasing emergency updates for vSphere ESXi to resolve the underlying cause.

These recurring issues highlight the complexities and interdependencies involved in maintaining virtual environments and ensuring compatibility across different hardware and software configurations. Administrators are advised to keep their systems updated and monitor official channels for patches and workarounds to mitigate such issues effectively.