Microsoft’s .NET Framework 3.5 development platform, which dates back to November 2007, is no longer included as an optional Windows component. Microsoft has changed its deployment model to standalone installer status for future Windows versions.
In a bulletin published February 5, Microsoft said that beginning with Windows 11 Insider Preview Build 27965, .NET Framework 3.5 must be obtained as a standalone installer for applications that require it on newer major versions of Windows. The change also applies to future platform releases of Windows but does not affect Windows 10 or earlier Windows 10 releases through 25H2.
Microsoft said the change for .NET Framework 3.5 aligns with the product’s life cycle, as .NET Framework 3.5 approaches its end of support on January 9, 2029. Customers are encouraged to begin planning migrations to newer, supported versions of .NET. Guidance including installers, compatibility notes, and recommended migration paths has been published on Microsoft Learn for users with applications that depend on .NET Framework 3.5.
