Servicing stack updates
What is a servicing stack update?
Servicing stack updates provide fixes to the servicing stack, the component that installs Windows updates. Additionally, it contains the "component-based servicing stack" (CBS), which is a key underlying component for several elements of Windows deployment, such as DISM, SFC, changing Windows features or roles, and repairing components. The CBS is a small component that typically doesn't have updates released every month.
Why should servicing stack updates be installed and kept up to date?
Servicing stack updates improve the reliability of the update process to mitigate potential issues while installing the latest quality updates and feature updates. If you don't install the latest servicing stack update, there's a risk that your device can't be updated with the latest Microsoft security fixes.
When are they released?
Servicing stack update are released depending on new issues or vulnerabilities. In rare occasions a servicing stack update may need to be released on demand to address an issue impacting systems installing the monthly security update. Starting in November 2018 new servicing stack updates will be classified as "Security" with a severity rating of "Critical."
What's the difference between a servicing stack update and a cumulative update?
Both Windows client and Windows Server use the cumulative update mechanism, in which many fixes to improve the quality and security of Windows are packaged into a single update. Each cumulative update includes the changes and fixes from all previous updates.
Servicing stack updates improve the reliability of the update process to mitigate potential issues while installing the latest monthly security update release and feature updates. If you don't install the latest servicing stack update, there's a risk that your device can't be updated with the latest Microsoft security fixes.
Microsoft publishes all cumulative updates and SSUs for Windows 10, version 2004 and later together as one cumulative monthly update to the normal release category in WSUS.
Is there any special guidance?
Microsoft recommends you install the latest servicing stack updates for your operating system before installing the latest cumulative update.
Typically, the improvements are reliability and performance improvements that don't require any specific special guidance. If there's any significant impact, it will be present in the release notes.
- Servicing stack updates contain the full servicing stack; as a result, typically administrators only need to install the latest servicing stack update for the operating system.
- Installing servicing stack update doesn't require restarting the device, so installation shouldn't be disruptive.
- Servicing stack update releases are specific to the operating system version (build number), much like quality updates.
- Servicing stack updates can be delivered with Windows Update, or you can perform a search to install the latest available at Servicing stack update for Windows 10.
- Once a servicing stack update is installed, it can't be removed or uninstalled from the machine.
Simplifying on-premises deployment of servicing stack updates
With the Windows Update experience, servicing stack updates and cumulative updates are deployed together to the device. The update stack automatically orchestrates the installation, so both are applied correctly. Starting in February 2021, the cumulative update includes the latest servicing stack updates, to provide a single cumulative update payload to both Windows Server Update Services (WSUS) and Microsoft Catalog. If you use an endpoint management tool backed by WSUS, such as Configuration Manager, you'll only have to select and deploy the monthly cumulative update. The latest servicing stack updates will automatically be applied correctly. Release notes and file information for cumulative updates, including those related to the servicing stack, will be in a single KB article. The combined monthly cumulative update is available on Windows 10, version 2004 and later starting with the 2021 2C release, KB4601382.