Microsoft integrates Servicing Stack Updates (SSU) in cumulative Updates (LCU)

[German]Another small addendum from last week. Microsoft has announced it's plans to include the required Servicing Stack Updates (SSU) in future Latest Cumulative Updates (LCU). This could eliminate one cause of update errors.


Service Stack Update (SSU) internals

Microsoft has been releasing so-called Servicing Stack Updates (SSU) for Windows 10 on a regular basis for quite some time now. What is behind this and what are these updates supposed to do? The purpose of installing a service stack update is to improve the installation process of the operating system, including the installation of the update program. Servicing Stack Updates (SSUs) must always be placed on the machine separately from the cumulative updates for Windows 10 (and before installing them). I had pointed this out several times in various blog posts about Windows 10 updates. If this is ignored, the cumulative updates may cause installation errors. SSUs are not uninstallable. I had detailled this in the article Windows 10 Service Stack Update (SSU) internal explained in 2018. 

Infinite Theme Servicing Stack Updates (SSU)

It's a tiresome topic: the requirement that Servicing Stack Updates (SSUs) must always be brought to the machine separately from the cumulative updates for Windows 10 (and before LCUs are installed). This only works if the administrators can control this manually in WSUS or via Windows Update. With the automatic update installation, there have been and still are 'accidents' because the LCU is installed before the SSU. The installation of the LCU then fails with an error.

In summer 2019 a user had raised the issue of update installation problems under Windows 10 due to 'missing' current Servicing Stack Update (SSU) in SCCM-UserVoice (see Windows 10: SSU issue addressed in SCCM UserVoice). It seems that there is no mechanism in Windows to control the order of update installations. So much for preliminary remarks.

Microsoft explains the changes

It took a long time for Microsoft to get into the hooves. But on September 8, 2020, Aria Carley of Microsoft published the article Simplifying on-premises deployment of servicing stack updates. And on September 11, 2020, Microsoft published the support article Description of Software Update Services and Windows Server Update Services changes in content for 2020.

Aria Carley's article states that feedback from the user community has been heard and that steps will be taken to improve the update experience. The following is again confirmed:


  • To keep devices up to date, IT administrators who manage devices using on-premise methods must select and deploy the correct service stack update (SSU) with the latest cumulative update (LCU).
  • In some cases, a specific version of the SSU must already be installed to install the latest LCU. If the required SSU is not already installed on the device, the LCU cannot be installed.

This is confusing for many users and you have to make sure every month that the SSU conditions are met. Microsoft has therefore decided to bundle both the latest Cumulative Update (LCU) and the required Servicing Stack Update (SSU) in one package. The cumulative monthly update should then contain the cumulative fixes of the month and, if applicable, the corresponding service stack updates for that month. The update stack automatically orchestrates the installation so that both are applied correctly.

Microsoft wants to make sure that these 'single update packages' are also provided correctly in the Microsoft Update Catalog and via WSUS.  When administrators use WSUS supported management tools, such as Configuration Manager, they must select and deploy the monthly cumulative update. The latest SSU is automatically applied correctly.

However, if Dynamic Update packages are purchased before deployment and applied to existing Windows 10 images, the latest SSU is no longer available as a separate package in the Microsoft catalog. If a process requires the SSU, administrators should simply use the new combined SSU and LCU package.

Important: For now, this applies to Windows 10 version 2004 and later. Later, Microsoft plans to extend this to other Windows 10 versions. There are no dates or details about this. Blog reader Karl also complains in the comments that Windows 10 2004 and 20H2 appear in the same category as Windows 10 190x in WSUS and asks for a separate category. 

It remains to be seen whether these SSU-missing installation problems will be solved. And I'm already asking myself what the reasons are that Microsoft has to patch the servicing stack of Windows 10 all the time.

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