Microsoft released .NET 11 on 10 November 2026, on the first day of its free online .NET Conf 2026. It is a Standard Term Support (STS) release with two years of support; .NET 10 remains the Long Term Support option. Microsoft says STS and LTS get the same quality and servicing, only the length differs.
The same day, .NET 8 and .NET 9 reached end of support, according to Microsoft's announcement. Apps still running on them no longer get security fixes; the supported choices are now .NET 10 (LTS) and .NET 11 (STS).
C# 15 is the default language for net11.0. It adds union types, with switch expressions that check you handled every case, closed hierarchies, arguments in collection expressions, extension indexers and labeled break and continue. In ASP.NET Core, validation can run asynchronously, OpenAPI 3.2 is now the default, System.Text.Json understands unions and SignalR can refresh authentication. .NET MAUI now runs on CoreCLR by default, and Entity Framework Core 11 requires .NET 11.
The SDK enables a Native AOT CLI host and a warm MSBuild server by default, and ships an MCP server template (dotnet new mcpserver) for building tools that AI agents can call. Microsoft cites "hundreds of runtime optimizations" but gives no overall speed figure in the announcement. Runtime Async is still a preview you switch on per project, and Blazor's AI components are experimental.
The release drew 223 points and 156 comments on Hacker News within hours.
