Windows 10: News from SSU integration in CUs (August 2021)

Windows[German]Another small addendum about Windows 10 and the integration of the Servicing Stack Updates (SSUs) into current Cumulative Updates (LCUs). Due to massive problems with the installation of the cumulative updates from June and July 2021, Microsoft has released a separate SSU for August. And it seems that they have started to integrate that SSU into the cumulative updates for Windows 10 version 1909 as well.


Microsoft has actually been releasing so-called Servicing Stack Updates (SSU) for Windows 10 on a regular basis for quite some time. The purpose of installing a Servicing Stack Update is to improve the installation process of the operating system, including the installation of the update program.

Servicing Stack Updates (SSUs) have historically always had to be applied to the machine separately from (and before installing) Windows 10 cumulative updates. If a current SSU is missing, installation errors can occur when installing the cumulative updates.

SSU integration in LCUs

In September 2020, Microsoft announced in the Techcommunity post Simplifying on-premises deployment of servicing stack updates that it would start integrating servicing stack updates (SSUs) into the latest cumulative updates (LCUs) for Windows 10. This should solve the issue of the LCU being found and installed first during the update search, and then errors occurring if necessary.

In the Techcommunity article, there is also the note that Microsoft released February 9, 2021 SSUs for Windows 10, versions 1909 and 1809. These February 2021 SSUs are a prerequisite for receiving the new cumulative update (LCU and SSU together) for these versions of Windows 10.

I had reported about this in the blog post Microsoft integrates Servicing Stack Updates (SSU) in cumulative Updates (LCU). There you can also find the hint that this integration initially applied to Windows 10 version 2004 and higher. Later, this integration was to be extended to older Windows 10 versions as well. 


On August 10, 2021, the Techcommunity article Simplified deployment of Windows servicing stack updates: what's new was added. There, Microsoft announced that they would now extend the combined cumulative update features to more Windows versions. Since August 2021, the cumulative update packages with integrated SSU have been available for Windows 10 version 1809, Windows Server 2019 and Windows 10 version 1909.

As of Aug. 10, administrators can also use the Windows Insider Pre-release category in Windows Server Update Services (WSUS) to deploy the August 2021 monthly quality update and SSU together as a single package to devices running those versions.

Devices running Windows 10, version 1809, will first need the July 20, 2021 or later Servicing Stack Update (KB5004424) to take advantage of this new feature. Devices running Windows 10, version 1909, will need the Servicing Stack Update dated June 15, 2021 (KB5003974) or later.

Update KB5005260 fixes Windows 10 LCU installation issue

In recent months, however, it turned out that Microsoft's approach to integrating the respective SSU into the cumulative update (LCU) did not really work. Machines missing the May 11, 2021 update KB5003173 caused installation errors in the cumulative updates for the following months of June and July. I had mentioned the problem in the blog post Windows 10 SSU: Hurdles, bugs and new version KB5003974 (June 15, 2021).

As of June 22, 2021, there was already the Techcommunity post Issue: The June 2021 Windows 10 security update is reported as not applicable, ,hich then confirmed these problems. Blog reader Thomas already pointed out in this German comment on August 11, 2021 that there is a separate servicing stack update KB5005260 for Windows 10 version 2004, 20H2 and 21H1. This can be obtained from Windows Update as well as downloaded directly from the Microsoft Update Catalog. The update is also available in Windows Server Update Services (WSUS) (blog readers had pointed this out in comments).

The explanation for this swing can be found in the Techcommunity post Known Issue: The June 2021 Windows 10 security update is reported as not applicable. An addendum states::

The August 2021 servicing stack update (SSU) (KB5005260) will satisfy the June 2021, July 2021 and July 2021 OOB security updates pre-requisite for the May 2021 security update.

Note: The August 2021 SSU (KB5005260) is only applicable to devices that have not already installed the May, June, or July 2021 security updates.

So the concession that the one-time release of the KB5005260 update is intended to fix the installation problems of June and July 2021. However, the update will only be installed if the security updates (LCUs) from May to July 2021 could not be successfully installed. So it looks like in order to simplify something, Microsoft has to make it all complicated beforehand.

Similar articles
Microsoft integrates Servicing Stack Updates (SSU) in cumulative Updates (LCU)
Windows 10 SSU: Hurdles, bugs and new version KB5003974 (June 15, 2021)

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