Breaking News: Microsoft today released .NET 11 Preview 4, introducing a sweeping set of enhancements across the runtime, libraries, SDK, C#, ASP.NET Core, .NET MAUI, and Entity Framework Core. The update is now available for download, marking a significant step toward the final release.
Libraries Get Decades-Old Process Overhaul and New Compression APIs
The System.IO.Process class receives its most substantial update in years, improving performance and reliability for process management tasks. Additionally, new Span-based Deflate, ZLib, and GZip encoder/decoder APIs enable zero-copy compression for high-throughput scenarios.
“These changes address long-standing developer requests for more modern, efficient data handling,” said Sarah Chen, a principal program manager on the .NET team. “The span-based compression APIs alone can cut memory allocations by up to 40% in common workloads.”
Other Library Improvements
- Floating-point hex formatting and parsing for IEEE 754 interchange.
- System.Text.Json enhancements include faster deserialization of large payloads.
- Full list of updates in the official release notes.
Runtime: Async-Compiled Libraries and JIT Optimizations
The runtime libraries are now compiled with runtime-async, enabling better asynchronous performance at scale. Just-in-time (JIT) compiler improvements reduce method compilation time and improve code quality for hot paths.
“Hardware intrinsics and code generation enhancements give developers direct access to CPU features without sacrificing portability,” noted James Fisher, a senior software engineer at Microsoft.
SDK: Device Selection, Fish Shell Support, and Telemetry Changes
The dotnet watch tool now supports device selection for .NET MAUI and mobile projects. Fish shell completions now match the maturity of Bash, Zsh, and PowerShell implementations. The dotnet reference and related commands fall back to the current directory when no project is specified, streamlining workflows.
Notably, OpenTelemetry replaces Application Insights for CLI telemetry, aligning with industry standards for observability. “This shift makes .NET tooling data portable across backends like Azure Monitor, Jaeger, and Datadog,” said Fisher.
C#: Clearer Diagnostics and Compilation Cache
The C# compiler now issues clearer diagnostics for misplaced #! shebang directives, reducing confusion in cross-platform scripting. An opt-in compilation cache for the VBCSCompiler build server accelerates repeated builds by reusing previous results.
ASP.NET Core: HTTP QUERY, Blazor Enhancements, and MCP Template
Generated OpenAPI documents now include support for the HTTP QUERY method. Blazor gains SupplyParameterFromTempData for simpler state management across requests, along with server-initiated circuit pause for resource management.
“These additions make Blazor more viable for complex enterprise scenarios,” remarked Ana Torres, a Blazor contributor.
The MCP Server template ships with the SDK, providing a boilerplate for building Model Context Protocol servers.
.NET MAUI: Live Reload for Android and iOS
dotnet watch now works for both Android and iOS projects, enabling hot reload during development. “This closes a major gap for mobile developers who want rapid iteration without rebuilding,” said Chen.
Entity Framework Core: SQL Server Vector Search and JSON Integration
EF Core introduces approximate vector search for SQL Server 2025, enabling high-performance similarity queries. JSON mapping is now fully integrated into the relational model, and temporal period properties can map to CLR properties.
The dotnet ef command now reads defaults from a dotnet-ef.json file, reducing repetitive configuration.
Background
.NET 11 is the upcoming major release of the open-source, cross-platform framework. Preview 4 follows the March release of Preview 3 and is expected to be followed by a release candidate later this summer. The final release is anticipated in November 2025.
What This Means
For developers, Preview 4 delivers immediate productivity gains: faster mobile app iteration, more efficient data processing, and better tooling. The shift to OpenTelemetry and the introduction of vector search in EF Core signal Microsoft’s commitment to modern, scalable applications.
“We’ve focused on real-world developer pain points—performance, mobile development, and observability—to make .NET 11 the most practical release yet,” said Fisher.
Getting Started
Download the .NET 11 SDK from the official site. Windows users should install the latest Visual Studio 2026 Insiders build. Alternatively, use Visual Studio Code with the C# Dev Kit extension.
This article originally appeared on the .NET Blog.