Microsoft has announced that Windows Server 2025 hotpatching—a service allowing administrators to install security updates without system restarts—will require paid subscriptions starting July 1, 2025. The service, currently available in preview at no cost, will transition to a subscription model priced at $1.50 USD per CPU core per month.

## Key Details About the Service

“Hotpatching is taking what was previously an Azure-only capability and making it available to Windows Server machines outside of Azure through Azure Arc,” Microsoft explained in their announcement. The company encourages administrators to test the feature for free before the general availability launch, but warns current testers to disenroll by June 30 to avoid automatic subscription enrollment.

To implement hotpatching in multi-cloud or on-premises environments, users will need:
– A Hotpatch service subscription
– An Azure Arc-connected server running Windows Server 2025 Standard or Datacenter

## How Hotpatching Works

When enabled, hotpatching deploys security updates by patching in-memory code of running processes without requiring restarts after each installation. However, Microsoft notes that certain updates still require reboots, including:
– Non-Windows updates (such as .NET patches)
– Windows non-security updates
– Updates delivered through the regular Windows update channel

## Availability Timeline

– February 2022: Hotpatching became available for Windows Server 2022 Datacenter: Azure Edition
– September 2024: Public preview testing began for Windows Server 2025
– November 2024: Testing expanded to Windows 11 24H2 and Windows 365
– April 2025: Hotpatch updates become generally available for Windows 11 Enterprise 24H2 on x64 systems
– July 2025: Subscription requirement begins for Windows Server 2025 hotpatching

Administrators interested in enabling hotpatching can connect their servers to Azure Arc and configure the option through Azure Update Manager in the Azure Portal.