New Windows 11 24H2 September 2025 Update – New Features in the Main Release (Build 26100.6584 or KB5065426)

In this article, we will talk about the latest Windows 11 Update for the 24H2 Main Release, which is the Build 26100.6584 or KB5065426.

For those of you who are not familiar with how Windows 11 Updates for the Main Release work, I will explain it to you in the following lines.

Every month Windows 11 has a B and a C Release for Windows 11. Usually, the B Release is launched on the second Tuesday of the month and contains all the features that were tested in the previous month’s C Release.

New Improvements in this Update

• This update addresses security issues for your Windows operating system. 
• [App compatibility (known issue)] ​​​​​​​Fixed: Addresses an issue that caused non-admin users to receive unexpected User Account Control (UAC) prompts when MSI installers perform certain custom actions. These actions might include configuration or repair operations in the foreground or background, during the initial installation of an application.This issue could prevent non-admin users from running apps that perform MSI repairs, including Office Professional Plus 2010 and multiple applications from Autodesk (including AutoCAD). This fix reduces the scope for requiring UAC prompts for MSI repairs and enables IT admins to disable UAC prompts for specific apps by adding them to an allowlist.For more information, see Unexpected UAC prompts when running MSI repair operations after installing the August 2025 Windows security update.
• [File server] This update enabled auditing SMB client compatibility for SMB Server signing as well as SMB Server EPA. This allows customers to assess their environment and identify any potential device or software incompatibility issues before deploying the hardening measures that are already supported by SMB Server. For detailed guidance, see CVE-2025-55234.
• [Input]
  • Fixed: This update addresses an issue that caused certain apps to stop responding input in some input method scenarios.
  • Fixed: This update addresses an issue that caused some Internet Information Services (IIS) modules to disappear from IIS Manager, preventing users from configuring IIS using the IIS Manager interface.
• [Networking (known issue)] Fixed: This update addresses an issue that affects audio in apps using the Network Device Interface (NDI). Audio stutters when Display Capture is on in OBS Studio Application. This can occur after installing KB5063878. 

For an in-depth list of other features and fixes that are rolling out, you can check this article.

Windows 11 Servicing Stack Update – 26100.5074

This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. Servicing stack updates (SSU) ensure that you have a robust and reliable servicing stack so that your devices can receive and install Microsoft updates. 

For more info about this Update, you can check this article from the Microsoft Blog.

For a more in-depth presentation of the New Update, you can watch the video below from the YouTube channel.