Revolutionizing Server Management: Hotpatching in Windows Server 2025

If you've ever had to plan downtime for server patches and updates at 3 AM to keep your mission-critical systems humming along, you're probably familiar with the headaches and heartburn that come along with it. But here’s some good news straight out of Redmond's kitchen: Windows Server 2025 introduces Hotpatching, an innovative feature designed to apply security patches without rebooting the server. Welcome to the future of patch management, where disruptions are the exception, not the rule.
This guide breaks it all down for you—the prerequisites, setup process, and how it actually works so you can hit the ground running.

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What Is Windows Server Hotpatching?​

At its core, Hotpatching is like applying a band-aid to a running system without ever having to stop the machine. It's Microsoft's star feature built into Windows Server 2025 (and currently still in public preview). What makes it truly transformative is this:

• Reduced downtime: Instead of multiple reboots throughout the year, Hotpatching trims it down to just four planned reboots annually—January, April, July, and October during the infamous "Patch Tuesday." Other months are hotpatch-only.
• In-memory updates: Patches are applied directly to running processes, saving you from reboot juggling.
• Simplified patch orchestration: Smaller and faster patches mean lower CPU usage during updates and quicker installations.

This isn't just convenience—it's strategic. For IT admins, reduced downtime translates to uninterrupted business operations, better resource availability, and fewer sleepless nights.

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A Brief History: Hotpatching’s Beginnings​

Hotpatching isn’t entirely new. Microsoft previously tested the waters with Windows Server 2022 Azure Edition, bringing hotpatch features to Azure-hosted virtual machines (VMs). It has since expanded its scope beyond Hyper-V into other environments, such as VMWare and any platform supporting Virtualization-Based Security (VBS). With Windows Server 2025, the intention is to bring Hotpatching to broader enterprise landscapes, including physical servers.

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Why Should You Care?​

Microsoft's approach to Hotpatching is deliberate—it’s about addressing the pervasive challenge of server maintenance:

• Faster deployment, less hassle.
• Optimized resource allocation: None of that dreaded performance lag mid-patch.
• Enhanced security posture: Updates happen more frequently without the downtime risk.

From a security perspective, this means no more delaying patches due to inconvenient reboots, reducing the window of vulnerabilities.

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Who’s on the Guestlist? Prerequisites You Need to Know​

1. Supported Server Version:
   • Hotpatching only works with Windows Server 2025, specifically Standard and Datacenter editions.
2. Connectivity:
   • A secure and stable Internet connection is required to access Microsoft's Windows Update servers.
   • Servers need to register with Azure Arc, meaning the Azure Connected Machine Agent (CMA) must be installed.
3. Virtualization-Based Security (VBS):
   • VBS is a mandatory requirement. It isolates and protects critical processes using hardware-based virtualization. For Hotpatching, VBS enables critical in-memory updates without compromising the integrity of the system.

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Step-by-Step Guide to Enabling Hotpatching​

Here’s how to get Hotpatching running on your Windows Server 2025:

1. Verify Virtualization-Based Security (VBS)​

To check if VBS is already enabled:

• Run msinfo32.exe via Start Menu -> Run or Command Prompt.
• Look for the Virtualization-Based Security field on the System Summary page.
• If displayed as "Enabled," you're good; otherwise, follow these steps:
  To enable VBS via Command Prompt:
  

  cmd
  Reg add "HKLM\SYSTEM\ControlSet001\Control\DeviceGuard" /v "EnableVirtualizationBasedSecurity" /t REG_DWORD /d 1 /f

• Reboot your system, recheck in msinfo32, and move forward.

2. Connect Your Server to Azure Arc​

• Install the Azure Connected Machine Agent (CMA) to register your server with Azure Arc.
• This step is required to manage updates through Azure.

3. Enable Hotpatching in Azure Portal​

• Open the Azure Portal, locate your server under “Capabilities.”
• Select Hotpatching (Preview) and confirm that VBS is flagged as ON.
• Check the option for "I want to license this Windows Server to receive monthly hotpatches" and click Confirm.

After this, the server automatically enrolls in the program. Following normal reboot patch cycles for January and April, hotpatches will kick in for February, March, May, June, etc.

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Verifying Hotpatching is Active​

Not sure if Hotpatching is working? Here’s how you can confirm:

Method 1: Azure Portal​

1. Go to Operations -> Updates.
2. Perform a “Check for Updates” action. If hotpatch-capable updates are detected, the system is ready for monthly Hotpatch cycles.
3. You'll see Hotpatch Enabled notifications in the dashboard.

Method 2: Windows Update History​

On the server itself:

• Open the Windows Update settings.
• Look under Update History for installed patches labeled “(Hotpatch).”

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Behind the Scenes: How Does Hotpatching Work?​

Hotpatching leverages VBS (hello, secure kernel!) to apply updates directly to processes loaded in memory. Instead of shutting down, replacing files, and rebooting, the server creates a secure runtime environment where patches can take effect immediately.
Think of it like swapping a plane’s engine mid-flight—without losing altitude. The system runs seamlessly while ensuring the patch applies safely.

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Best Practices to Keep in Mind​

1. Plan Patch Tuesday: Even though most months are now reboot-free, the quarterly cycles still demand attention.
2. Monitor Regularly: Always check in both the Azure Portal and Windows Update logs to ensure everything is ticking along.
3. Stay Updated on Prerequisites: Ensure VBS remains enabled; any misconfigurations could block updates.

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The Bigger Picture: What This Means for IT Administrators​

Hotpatching isn't just a technical upgrade—it’s Microsoft doubling down on the priority of uninterrupted enterprise operations. For environments that demand 24/7 uptime, such as banks and hospitals, the ability to patch on-the-fly without rebooting is revolutionary. And let’s not ignore the economic benefits of reduced downtime, which translates directly to improved SLAs and happier end-users.

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Wrapping Up – Is Hotpatching Worth It?​

In a word: Yes.
For organizations already betting big on Windows Server 2025, Hotpatching represents a game-changer in streamlining operations while plugging security holes on the go. Sure, public preview comes with its quirks (and likely a few debugging moments), but the payoff—greater control, efficiency, and reliability—is impossible to ignore.
Start your engines, IT pros. Windows Server 2025 Hotpatching could be your ticket to an era of seamless updates and sleepless nights left in the dust.
Got questions? Ready to share your Hotpatching experience? Let us know in the comments below!

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Source: Petri IT Knowledgebase Enable Windows Server 2025 Hotpatching: A Step-by-Step Guide