Microsoft is removing an optional Windows feature

While Windows as an operating system is pretty feature-packed already, Microsoft also has a ton of other optional features that are disabled by default in fresh installations. A notable example of this is the excellent Windows Sandbox experience that can be optionally turned on through the Windows Features menu. Now, Microsoft has announced that it is removing an optional Windows component that was previously found in these features.

The component in question is .NET Framework 3.5. Although .NET Framework 4.8 Advanced Services was enabled by default in Windows 11, the previously mentioned component was not, and had to be enabled for legacy applications which required it. Now, Microsoft is removing it from the optional Windows Features in future versions of the OS, shifting the deployment model to a standalone installer.

Microsoft kicked off this change from build 27965 of the Windows 11 Insider Preview that was rolled out to the Canary Channel in October 2025. As such, this removal impacts any build released beyond that point as well as future general releases of Windows. It does not affect Windows 10 or Windows 11 releases up until version 25H2. The removal of .NET Framework 3.5 also affects these components, which can no longer be optionally installed directly either:

• ASP.NET 3.5
• .NET Extensibility 3.5
• WCF HTTP Activation
• WCF non-HTTP Activation

The Redmond tech giant believes that this change "aligns with the product's lifecycle", which ends on January 9, 2029. Additionally, it encourages customers to upgrade to newer and supported versions of the component.

The good news is that Microsoft has detailed all of these changes in a dedicated document where it has also recommended the process that can be leveraged to install .NET Framework 3.5 through the offline installer and some of the other associated components through PowerShell scripts. You can read more about it here.