Microsoft has officially released .NET 11, announced on 10 November 2026 at .NET Conf 2026.

The headline feature is C# 15, which brings union types to the language, letting developers model values that can be one of several types more cleanly. The SDK is faster too, with a Native AOT CLI host that speeds up everyday tooling.

For data and AI work, Entity Framework Core 11 adds experimental SQL Server vector search, bringing AI-ready search to .NET apps. Runtime Async, a new way to run async code with less overhead, is available now as a preview, opt-in feature.

.NET 11 also marks a changing of the guard: .NET 8 and .NET 9 reach end of support, while .NET 11 ships with two years of support, until November 2028.

Why it matters: .NET 11 is the new long-term foundation for building web, desktop, mobile and cloud apps on Microsoft's platform - modern language features, faster tooling and AI-ready data search in a single upgrade.