Microsoft Unveils .NET 11 RC1 with New Language Features
Microsoft unveiled .NET 11 Release Candidate 1, marking the initial candidate release in the .NET 11 development cycle. This version includes a production-ready license, enabling development teams to deploy applications using it immediately. Compatibility extends to Visual Studio 2026 Insiders and Visual Studio Code with the C# Dev Kit extension.
.NET 11 RC1 establishes C# 15 as the default language version for projects targeting the framework. Key features introduced during the preview phase, such as collection expression arguments, union types, and non-virtual static interface members, have now reached stability.
Language Updates
Developers no longer need preview language settings to utilize union types, as Roslyn now implements the final CSharp15 naming conventions. A new API provides analyzer access to union cases, while Unsafe Evolution remains a preview feature requiring its own activation flag.
The release also updates F# 11 to default status, stabilizing record spreads and direct delegate construction. Additionally, string interpolation now generates String.Concat calls instead of relying on the reflection-based printf engine, improving compatibility with trimming and Native AOT compilation.
SDK and Testing Updates
The .NET SDK introduces expanded cross-platform testing capabilities, allowing dotnet test to execute projects targeting Android, iOS, macOS, and Mac Catalyst. New project templates accompany these platforms, while enhanced run-level options now support timeout configurations, failure thresholds, and isolated result directories for each test application.
Container publishing optimizations ensure consistent image digests across builds when SOURCE_DATE_EPOCH is specified, while redundant uploads are avoided if the manifest already exists in the target registry. ASP.NET Core finalizes SignalR authentication refresh APIs for both server-side and .NET client implementations, with equivalent support extended to the TypeScript client.
Community Reaction and Additional Updates
Discussions on Reddit reflected largely pragmatic feedback, with multiple developers noting that migrating existing projects to .NET 11 required minimal adjustments, primarily an SDK installation and minor project file modifications. Jon Galloway, a member of Microsoft’s .NET team, clarified in the thread that release notes highlight changes since the last preview rather than since .NET 10.
Further updates include file-based program support in dotnet format, TLS channel binding for Negotiate authentication, and standardized Blazor browser option names. Full release notes for the .NET SDK, C#, F#, ASP.NET Core, and .NET MAUI are available through the official GitHub repository.
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