Microsoft has announced that its preview of hotpatching for on-prem Windows Server 2025 will become a paid subscription service in July.

Hotpatching allows software updates to be applied without requiring a reboot. It’s a common approach that’s available for the Linux kernel, VMware products, and the Xen hypervisor. Admins like it because it allows security updates to be implemented without requiring reboots – and therefore without having to find a change window or convenient moment for an outage.

Microsoft already offers hotpatching for Windows Server: Azure Edition and version 2022 running in its Azure cloud. The company says its Xbox team is a big user.

In August 2024 the Windows behemoth announced a preview of the same functionality for Windows Server 2025 running in Azure.

A month later, the software giant teased a preview of hotpatching for Windows Server 2025 implementations controlled by its Arc hybrid-and-multicloud management tool.

That preview meant hotpatching came to Windows Server 2025 Standard and Datacenter edition, and made it possible to use hotpatching on-prem.

“This feature will be a game changer; simpler change control, shorter patch windows, easier orchestration,” Microsoft’s general manager of Windows Server Hari Pulapaka wrote at the time, adding “and you may finally get to see your family on the weekends.”

Last Thursday Microsoft announced the preview will end on June 30th – and be replaced by a subscription service that costs $1.50/core/month.

A post by Windows Server Product Marketing Manager Janine Patrick and Senior Program Manager Artem Pronichkin explained that the service aims to deliver eight hotpatches each year.

“It follows a three-month cycle with the first month as a baseline month (monthly cumulative update) followed by two months of hotpatches. During baseline months the machines will need a reboot,” the pair wrote, before explaining that the baseline months are January, April, July and October. They also advised “On rare occasions, for security reasons we may have to ship a non-hotpatch update during a hotpatch month which will also need a reboot. But the goal will be to provide up to eight hotpatches in a year.”

The pair argue hotpatching “can decrease the ‘window of vulnerability’ which can result if an administrator might normally delay an update and restart after a Windows security update is released” and also argue that “hotpatching can save significant time and ease the inconvenience of a traditional ‘patch Tuesday’.”

Users will not be required to adopt hotpatching: Microsoft will continue to deliver software updates on its current schedule.

While Windows Server 2025 machines will need to be managed by Arc to use hotpatching, using Arc for this new offering won’t incur a cost.

Those who are testing the hotpatching preview will automatically be rolled onto subscriptions from July 1st. To avoid that, disenroll before June 30th.

Azure Editions of Windows Server will continue to get hotpatching at no cost.