Microsoft has released .NET 11 Preview 1, officially starting the development cycle for the next Standard Term Support (STS) version of its cross-platform framework. Microsoft plans the final release for November 2026, with two years of support after launch.
This first preview introduces updates across the runtime, SDK, core libraries, C#, F#, ASP.NET Core, Blazor, and .NET MAUI. While Microsoft highlights performance and tooling improvements, early community reactions remain mixed.
Runtime Changes Focus on Async Debugging and WebAssembly
.NET 11 adds runtime-level async infrastructure designed to improve debugging in heavily asynchronous applications. The runtime can now track async call paths more accurately, which helps developers inspect call stacks beyond the first await.
Microsoft also begins migrating WebAssembly from the Mono runtime to CoreCLR. Preview 1 introduces early CoreCLR support for WebAssembly and starts bringing up a Wasm-targeting RyuJIT. This shift aims to deliver better performance, JIT support, and long-term consistency across .NET platforms.
Libraries Add Zstandard and Performance Improvements
The .NET libraries gain native Zstandard (Zstd) compression support, delivering faster compression and decompression while maintaining competitive compression ratios. Developers now get streaming, one-shot, and dictionary-based APIs through System.IO.Compression.
Other library improvements include:
- BFloat16 floating-point type support
- FrozenDictionary enhancements
- Time zone conversion performance improvements
- Expanded Rune support across strings and text writers
- New cryptographic verification APIs
These updates target real-world performance gains rather than surface-level features.
SDK and CLI Get Practical Quality-of-Life Updates
The .NET 11 SDK improves daily workflows with several CLI upgrades:
dotnet runnow supports interactive target framework and device selectiondotnet testaccepts positional argumentsdotnet watchexpands Hot Reload support, including reference changes- New built-in analyzers improve diagnostics and code quality
Developers have already called out interactive target selection as one of the most useful additions in Preview 1.
C# 15 Introduces Collection Expression Arguments
C# 15 debuts collection expression arguments, allowing developers to pass capacity, comparers, or other constructor parameters directly inside collection expressions.
Example syntax:
List<string> names = [with(capacity: values.Count * 2), ..values];This feature has sparked debate. Some developers welcome the flexibility, while others criticize it as unnecessary syntax complexity. Community discussions across Reddit and GitHub highlight concerns about “language bloat” and analyzer overreach.
F# 11 Cleans House and Speeds Up Builds
F# 11 enables parallel compilation by default and delivers faster builds for computation-expression-heavy code. Microsoft also removes long-standing ML compatibility features, eliminating thousands of lines of legacy compiler code.
Keywords previously reserved for ML compatibility now work as regular identifiers, signaling a clean break from F#’s early OCaml heritage.
ASP.NET Core, Blazor, and MAUI Get Targeted Enhancements
ASP.NET Core and Blazor introduce new UI and infrastructure features, including:
- EnvironmentBoundary component for environment-specific rendering
- Improved OpenAPI support for binary responses
- SignalR configuration updates for interactive server components
.NET MAUI now enables XAML source generation by default, improving build times and runtime performance. On Android, CoreCLR becomes the default runtime, reducing startup time and improving consistency across platforms.
While performance updates earn praise, many developers express concern about the annual release cadence and growing language complexity. Some argue that rapid version cycles force features that provide limited real-world value.
Others push back against Microsoft’s growing emphasis on agentic AI in future roadmaps, urging the team to focus on stability, Native AOT maturity, and core framework reliability instead.
Developers can install the preview today using the .NET 11 SDK and test it with Visual Studio 2026 Insiders or Visual Studio Code with the C# Dev Kit. Production use is not recommended, but Preview 1 offers a clear look at where .NET heads next.
