If you’re running Windows Server 2022 and using Hyper-V virtual machines, especially those built for extra data privacy, you might have hit a frustrating issue: your VMs could unexpectedly freeze or restart. Microsoft has quickly released an emergency update, KB5061906, to tackle this problem head-on. This out-of-band update is crucial for affected users, particularly those relying on Azure confidential VMs, to restore stability and prevent service disruptions.
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Windows Server 2022 logo on a blurred server background, representing a critical emergency update for Hyper-V virtual machines.
The Problem: Virtual Machines Freezing or Crashing
The core issue affects Windows Server 2022 systems using Microsoft’s Hyper-V virtualization feature. Some virtual machines running on these servers have been experiencing unexpected behavior, either freezing completely or restarting without warning.
This instability primarily impacts what are called Azure confidential VMs. These are special virtual machines designed with advanced security features that protect data not just when it’s stored or sent over a network, but critically, while it’s actively being processed. This is vital for handling highly sensitive workloads. Microsoft notes that while the issue mainly hits these confidential VMs on Azure, standard Hyper-V setups could potentially see problems in rare cases, especially with preview or pre-production configurations. The glitches affect service availability and often require someone to manually step in to fix things.
Microsoft traced the root cause to a specific path within the system related to memory addressing (a “direct send path for a guest physical address”).
The Solution: Emergency Update KB5061906
To fix this, Microsoft has rolled out an emergency, or “out-of-band” (OOB), cumulative update specifically for Windows Server 2022: KB5061906. Being “out-of-band” means it’s released outside of the usual monthly update schedule, highlighting the critical nature of the bug it addresses. This new update replaces any previous updates for this specific fix.
How to Get the Fix
Here’s something important to note: this emergency update will not install automatically through your standard Windows Update process.
To get KB5061906, you need to download it manually. You can find the standalone installer package (an MSU file) on the Microsoft Update Catalog website. Once downloaded, you install it like a regular update package.
Who Needs This Update?
Microsoft offers clear guidance on who should install KB5061906:
- Install if you are affected: If you are running Windows Server 2022 with Hyper-V and are experiencing the freezing or restarting issue with your VMs, particularly Azure confidential VMs, you should install this update.
- Consider if you haven’t updated recently: If your IT environment includes Windows Server 2022 devices running Hyper-V, and you haven’t yet applied the May 2025 Windows security update (KB5058385), Microsoft recommends applying this OOB update (KB5061906) instead if you are potentially affected by the VM issue.
- Skip if you’re not affected: If your organization uses Windows Server 2022 but is not experiencing this specific Hyper-V VM issue, you do not need to install KB5061906.
Not the First Time: Past Server Update Challenges
This isn’t the first instance where Windows Server updates have needed quick fixes related to virtualization or containers. Just last month, Microsoft released emergency updates to resolve an issue preventing Windows containers from launching on several Server versions, including 2019 and 2022. You can read more about those specific fixes here.
Going back further, in October 2023, standard security updates for Windows Server 2019 and 2022 caused Hyper-V VMs to have boot issues and fail to start. Emergency updates were also needed in January and December 2022 to fix problems creating new Hyper-V VMs and preventing VMs from booting up after updates. These previous incidents highlight the complexity of server environments and the critical role of timely patches when issues arise.
In Summary
Microsoft’s emergency update KB5061906 is a critical fix for Windows Server 2022 users experiencing unexpected freezing or restarting with Hyper-V virtual machines, especially those used for sensitive data on Azure. Because this update isn’t automatic, affected administrators must manually download and install it from the Microsoft Update Catalog to restore stability. If you rely on Windows Server 2022 Hyper-V VMs, particularly confidential ones, checking for and applying this patch if you’re experiencing the problem is highly recommended.
