How to Fix Windows 11 24H2 and Windows Server 2025 Virtual Machines Crashing After July Updates?

Why Are Your Windows Server 2025 VMs Crashing After July 2025 Updates?

The July 2025 security updates created serious problems for many IT teams. Virtual machines running Windows Server 2025 and Windows 11 24H2 stopped working. This issue affects Hyper-V, VMware ESXi, and Azure environments.

What Went Wrong

Microsoft released security updates on July 8, 2025. These updates broke virtual machines in three main ways:

• Boot failures - VMs won't start at all
• System freezes - VMs get stuck during startup
• Unresponsive systems - VMs hang with constant CPU usage

The root cause is Virtualization-Based Security (VBS). This security feature conflicts with older Hyper-V configurations.

Affected Systems

The problem hits these specific setups:

1. Windows Server 2025 virtual machines
2. Windows 11 24H2 virtual machines
3. Hyper-V configuration version 8.0 (older setups)
4. VMware ESXi 7.0 environments
5. Azure VMs without Trusted Launch

Real User Reports

IT professionals reported these exact symptoms:

• VMs freeze at 21% CPU usage consistently
• Boot process stops completely
• Systems become totally unresponsive
• Recovery console access required

One user had to run this command to fix their system:

dism.exe /image:C:\ /cleanup-image /revertpendingactions

This command removes the problematic July update.

The Technical Problem

Here's what happens inside your system:

Secure kernel initialization fails when VBS tries to start. The July updates changed how this process works. Older Hyper-V configurations can't handle the new security requirements.

Systems using Hyper-V version 8.0 face the worst problems. These are typically:

• VMs created on Windows Server 2016
• Systems upgraded to newer Windows versions
• Environments that haven't updated their VM configuration

Quick Workaround

Before applying the official fix, try this temporary solution:

1. Upgrade your Hyper-V configuration from version 8.0 to 12.0
2. Use the same VHDX file with the new configuration
3. Test the boot process - it should work normally

This workaround works because newer Hyper-V versions handle VBS correctly.

Official Microsoft Fix

Microsoft released update KB5064489 on July 13, 2025. This out-of-band update fixes the core problem.

What KB5064489 Does

The update addresses these specific issues:

• Fixes secure kernel initialization problems
• Restores VM boot functionality for affected systems
• Works with Hyper-V configuration 8.0 environments
• Supports both client and server Windows versions

How to Get the Update

The fix isn't available through Windows Update yet. You must:

1. Visit Microsoft Update Catalog manually
2. Search for KB5064489
3. Download the correct version for your Windows edition
4. Install manually on each affected VM

Supported Systems

KB5064489 works on:

• Windows 11 24H2 (all editions)
• Windows Server 2025 (all editions)

Prevention Steps

To avoid similar problems in the future:

• Update Hyper-V configurations to version 12.0
• Test updates in non-production environments first
• Monitor VM performance after patch installations
• Keep backup restoration procedures ready

Impact on Different Platforms

Hyper-V Environments

Most reports come from Hyper-V users. The problem affects both standalone Hyper-V and Windows Server installations.

VMware ESXi

ESXi 7.0 users report similar freezing issues. The same KB5064489 update resolves these problems.

Azure Virtual Machines

Azure VMs without Trusted Launch experience boot failures. Microsoft prioritized this fix because it affects cloud customers directly.

Recovery Options

If your VMs are already broken:

1. Boot from recovery console
2. Run the DISM command to remove updates
3. Apply KB5064489 before reinstalling July updates
4. Upgrade Hyper-V configuration if possible

The recovery process typically takes 15-30 minutes per VM.

This situation shows why staged update deployment matters. Testing updates in isolated environments prevents widespread production failures.