[German]Microsoft offers a so-called hot patching option to Windows Server 2025, so that restarts can be suspended during the monthly security updates. Redmond has now announced that this feature need a subscription ans will be charged from July 1, 2025 onwards.
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Windows Server 2025 and hotpatching
When Windows Server 2025 was released on November 1, 2024, it was announced that this operating system would also support hotpatching. I had mentioned this feature in the blog post Windows Server 2025 LTSC released on November 1, 2024 and referred to the Microsoft Techcommunity post Now in preview: Hotpatch for Windows Server 2025 from September 2025.
It was sufficient to connect the Windows Server 2025 Datacenter machines to Azure Arc and subscribe to the hotpatching service via the Azure Arc portal. The deployment of the hotpatch updates can be managed natively on Azure via the Azure Update Manager. However, this was only available as a preview. Hotpatching is also available for Windows 11 24H2 (see Windows 11 24H2: Hotpatching now available).
What does hotpatching mean?
In the support article Hotpatch for virtual machines vfrom October 2023, Microsoft describes the chosen approach for hotpatching as a method for installing operating system security updates on supported virtual machines (VMs) under Windows Server Datacenter: Azure Edition without requiring a reboot after installation. The in-memory code of running processes is patched without the process having to be restarted. This approach has also been adopted in Windows 11 24H2 and Windows Server 2025.
The hot patch updates are distributed to authorized systems in the same way as the standard updates. However, devices that receive the hotpatch update will see a different KB number (for the hotpatch version) and a different operating system version than devices that receive the standard update, which requires a reboot. Hotpatch updates are released in a quarterly cycle:
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- Cumulative baseline month: In January, April, July and October, devices install the monthly fixed security update and reboot. This update contains the latest security fixes, cumulative new features and improvements since the last cumulative baseline update.
- The following two months: The devices receive hot patch updates that only contain security updates and do not require a reboot. These devices will catch up with the features and improvements with the next cumulative baseline month (quarterly).
Thanks to the eight planned hotpatch updates per year, this cycle reduces the number of restarts required for Windows updates from twelve to just four per year.
Windows Server 2025 hotpatching costs
Windows Server 2025 Standard or Datacenter is required to use hotpatching outside of Azure, e.g. on-premises or in multi cloud environments. In addition, the server must be connected to Azure Arc and subscribed to the hotpatch service.
In the preview, hotpatching for Windows Server 2025 was free of charge. However, the preview will expire on June 30, 2025 and administrators must unsubscribe by this date if they do not wish to subscribe to the hotpatching service. Otherwise, the subscription will start automatically on July 1, 2025.
From July 1, 2025, hot patching for Windows Server 2025 will be offered with the start of the subscription at a price of 1.50 US dollars per CPU core per month. Microsoft points this out in the article Tired of all the restarts? Get hotpatching for Windows Server from April 24, 2025 (this was noticed here). Further details and explanations can also be found there.
Of course, administrators can patch Windows Server 2025 with the regular monthly updates, which then requires a restart. The exciting question that arises for me: Are there enough scenarios where companies pay the required prices for the hotpatching subscription? And what happens with hotpatching if the update goes wrong? Would you want to pay for the hotpatching feature?
Similar articles:
Windows Server 2025 LTSC released on November 1, 2024
Windows 11 24H2: Hotpatching now available
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Next, Microsoft will charge you by how many hours a day you use your PC.