What are Windows 10 Service Stack Updates?

The following guide attempts to provide some clarification in regards to Servicing stack updates for Microsoft's Windows 10 operating system (applies to Windows 7 and 8.1 as well).

You may have come across a servicing stack update (SSU) before as a system administrator or home user. The description that Microsoft provides for these updates is rather vague most of the time.

When you check KB4132650 for Windows 10 version 1709 for instance, you get "This update makes stability improvements for the Windows 10 Version 1709 servicing stack" which does not really explain a whole lot.

KB4132216 for Windows 10 version 1607 reveals additional details, however about the update but Microsoft never really explained why it releases Servicing stack updates in first place.

Answers come from Microsoft Japan Windows Technology Support in form of an article. The article is in Japanese but good old Google Translate provides some insight.

The article provides the following information:

• What is a Service Stack Update?
• Details and impact when applying service stack updates.
• How to find out what the latest version of Service Stack Updates is for a particular version of Windows.
• What to do if you get "This update can not be applied to your computer".

What is a Service Stack Update?

A Service Stack Update updates Component Based Servicing (CBS) which handles the installation process for the operating system.

Cumulative updates in Windows 10 deliver only the newest versions of files or new files to the system when installed. Service Stack Updates need to be separate from the process as they are mandatory.

By installing updates, the following things may be improved:

• Ensure that updates can be installed as they may require a specific Service Stack version.
• Improve the reliability of the update process.
• Improve the performance.
• Other improvements outlined in the description of individual Service Stack Updates.

When you install a new SSU on a Windows 10 device all modules of the CBS component are updated. Windows 10 blocks the removal of Service Stack Updates on Windows machines and the only recourse that users and admins have when they run into issues after installing a new SSU is to restore an older version of the operating system.

It is quite difficult to find out which Service Stack Update is the latest for a particular version of Windows. The Japanese support team suggests two methods to find out about it:

• Run a search on Microsoft's Support website and go through the results.
• Set up a virtual environment and check which Service Stack Update gets installed.

Microsoft does not maintain a public list of Service Stack Updates that users and administrators could consult to find out about the latest version for a particular version of Windows.

Updates may have Service Stack Update prerequisites. If a required SSU is not installed, Windows throws the error message "This update can not be applied to your computer".

An event is written to the Windows log listing error 2149842967 as the cause. The error "translates" to "WU_E_NOT_APPLICABLE"; in other words, the update cannot be installed because a prerequisite update is missing.

Closing Words

Service Stack Updates (or Servicing Stack Updates) update only CBS components according to Microsoft. The Japanese article provides some insight into the current update process.