Microsoft releases emergency fix for Hyper-V freeze bug on Windows Server 2025

Microsoft has released an emergency fix for Windows Server 2025 to stop Hyper-V virtual machines from freezing or restarting without warning.

It’s worth noting that Azure confidential VMs mostly face this issue, as they’re built to secure data during processing. The freezes happen due to how the system handles memory paths using guest physical addresses (GPA). The bug could cause VMs to lock up or reboot randomly, impacting uptime and requiring manual fixes.

To solve this, Microsoft released KB5061977 as an out-of-band update. It replaces all earlier patches and targets a specific problem in the Hyper-V direct send path. According to Microsoft, this update mostly matters to Azure confidential VMs and shouldn’t affect standard Hyper-V setups, unless you’re using preview builds or test environments.

You can fix the Windows Server 2025 Hyper-V freeze via manual update

The fix won’t show up through Windows Update. If your servers are affected, you’ll need to download and install the standalone MSU package from the Microsoft Update Catalog. This isn’t the first time Hyper-V has had issues.

Microsoft has released several emergency patches this month. In mid-May, the company released Hotpatch KB5061258 for Windows 11 LTSC 2024. The latest out-of-band KB5061977 update comes right after Microsoft released KB5058502 Preview update that brought new Copilor shortcuts, and more to Windows 11 22H2 and 23H2.