The Update BureauWindows update notes mention three package types. They look alike, but each has a different job.
| Package | Plain-English job | How often |
|---|---|---|
| Cumulative update (LCU, "latest cumulative update") | The monthly update: security fixes and other improvements | Every month |
| Servicing stack update (SSU) | Fixes the part of Windows that installs updates | Only when needed |
| Enablement package (eKB) | A small switch that turns on a new Windows version | With a new version |
Cumulative update: install only the latest
Each cumulative update contains the changes and fixes of all the previous ones. If you skipped three months, the newest update still brings you fully up to date. This is why Patch Tuesday pages on this site point to one update, not a list, and why the monthly update history is easy to read.
Servicing stack update: bundled with the monthly one
The servicing stack is the component that installs Windows updates. It also underpins tools such as DISM and SFC. Since February 2021 the latest servicing stack update is included in the cumulative update, so Windows Update, WSUS and the Microsoft Update Catalog deliver one combined package, described in one KB article. For example, KB5127648 (October 2026) lists "Includes KB5127647" as its servicing stack part. An admin who deploys the monthly update does not need to pick the SSU separately. In rare cases Microsoft releases an SSU out of band first, when a problem would stop the monthly update from installing.
When you uninstall the monthly update, the servicing stack part stays installed. That is expected.
Enablement package: a fast switch
Some Windows 11 versions share the same files. Windows 11 24H2, 25H2 and 26H2 use one servicing branch, so most of the files of the newer version already arrive through the monthly updates, with the new features dormant. The enablement package switches them on. Microsoft describes it as "a small, quick-to-install switch", so the change takes one restart instead of a full reinstall. Build numbers show the result: 24H2 is build 26100, 25H2 is 26200 and 26H2 is 26300, and one monthly update (KB5127648) covers all three.
Not every release works this way. Windows 11 26H1 is built only for new devices with specific hardware and is not offered as an update from 24H2 or 25H2.
For IT admins
List the packages installed on a device with an elevated prompt:
> DISM /Online /Get-PackagesMicrosoft notes that most files of the newer version are already on 24H2 devices that have a recent monthly update installed, which is why the enablement package is so small. Keep devices current before you roll out a new version, and check the prerequisites in the KB article of the version you deploy. See also Windows 11, Windows 10 and Windows Server.
Sources
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