Table of Contents
Is .NET Framework 3.5 being removed from Windows 11 26H2, and how do you install it afterward?
What’s changing in Windows 11
Microsoft is moving .NET Framework 3.5 out of the Windows 11 base image in newer platform versions, so it won’t be included as an optional Windows component in those releases.
Starting with Windows 11 Insider Preview Build 27965, .NET Framework 3.5 is obtained via a standalone installer instead of being built-in.
What this means in practice
If a legacy app still requires .NET Framework 3.5, the app can keep working, but the runtime will need to be installed separately on newer Windows 11 versions.
Microsoft’s FAQ also notes that when you upgrade to the next Windows release, .NET Framework 3.5 does not persist, so you should expect to reinstall it after an upgrade.
Support timeline (and why it matters)
Support for the .NET Framework 3.5 standalone installer ends on January 9, 2029.
Microsoft is explicit that this aligns with lifecycle policy and recommends planning migration to newer, supported .NET versions rather than staying on 3.5 long-term.
Advisor guidance (what to do now)
- Identify dependency: Inventory which apps still require .NET Framework 3.5 before rolling out newer Windows 11 versions broadly.
- Prepare installation: Use the standalone installer path documented by Microsoft for machines that must run those legacy apps.
- Plan modernization: Set a migration plan toward supported .NET (or updated app versions) ahead of the January 2029 support end date to reduce security and operational risk.