Welcome to our Q&A session covering the fourth preview release of .NET 11! This update brings a host of improvements across the .NET ecosystem—from the runtime and libraries to ASP.NET Core, .NET MAUI, C#, and Entity Framework Core. In this article, we break down the key changes into seven common questions, with detailed answers that highlight what developers can expect. Whether you're a seasoned .NET developer or just starting out, this guide will help you understand the new features and get started with the latest preview. Let's dive in!
1. What are the major highlights of .NET 11 Preview 4?
.NET 11 Preview 4 is packed with enhancements across multiple components. In the Libraries area, the Process class receives its biggest update in years, alongside new Span-based Deflate, ZLib, and GZip encoder/decoder APIs, floating-point hex formatting and parsing, and System.Text.Json improvements. The Runtime now compiles its libraries with runtime-async, plus JIT optimizations and updated hardware intrinsics and code generation. For the SDK, dotnet watch adds device selection for .NET MAUI and mobile projects, fish shell completions match other shells, and commands like dotnet reference fall back to the current directory. C# gets a clearer diagnostic for misplaced shebang directives and an opt-in compilation cache for the VBCSCompiler build server. ASP.NET Core introduces HTTP QUERY in OpenAPI documents, SupplyParameterFromTempData for Blazor, server-initiated Blazor Server circuit pause, and an MCP Server template. .NET MAUI now supports dotnet watch for both Android and iOS. Entity Framework Core adds approximate vector search for SQL Server 2025, full JSON mapping integration, and more. See the detailed sections below for more information.
2. What are the key updates in .NET Libraries?
The Libraries update in .NET 11 Preview 4 is significant, with the Process class receiving its largest overhaul in years—improving performance and usability. New Span-based APIs for Deflate, ZLib, and GZip encoder/decoder enable memory-efficient compression and decompression without allocations. Floating-point hex formatting and parsing have been added, making it easier to work with exact binary representations. System.Text.Json also gets enhancements for better serialization and deserialization. These updates aim to boost developer productivity and application performance. For a complete list, refer to the official library updates.
3. What improvements are in the .NET Runtime?
The Runtime now compiles its own libraries with the runtime-async feature, which can lead to better asynchronous performance. There are also several JIT optimizations that improve code execution speed. Hardware intrinsics and code generation have been updated to take advantage of modern CPU features, potentially accelerating math and data-processing operations. These changes make the runtime more efficient and responsive, especially for high-throughput applications. For details, see the runtime updates.
4. What’s new in the .NET SDK?
The SDK introduces several developer-friendly features. dotnet watch now supports device selection for .NET MAUI and other mobile projects, making it easier to test on specific emulators or physical devices. Fish shell completions have been added, bringing the same autocomplete experience as Bash, Zsh, and PowerShell. Commands like dotnet reference now fall back to the current directory if no path is specified, simplifying usage. Additionally, OpenTelemetry replaces Application Insights for CLI telemetry, providing a more modern and flexible monitoring approach. Check the SDK section for more.
5. How does C# improve in this preview?
In C#, Preview 4 focuses on developer experience and performance. It now provides a clearer diagnostic message when a #! shebang directive is misplaced (e.g., not at the very start of the file). This helps script authors quickly fix syntax errors. Additionally, there's an opt-in compilation cache for the VBCSCompiler build server, which can reduce compilation times in repeated builds. These improvements make coding and building in C# smoother. For full details, see the C# updates.
6. What are the highlights in ASP.NET Core and .NET MAUI?
ASP.NET Core gains support for the HTTP QUERY method in generated OpenAPI documents, aiding in creating more RESTful APIs. Blazor gets SupplyParameterFromTempData for passing data across requests, and server-initiated circuit pausing for better resource management. The MCP Server template is now included in the SDK, making it easy to build Model Context Protocol servers. .NET MAUI now supports dotnet watch for both Android and iOS development, enabling hot reload and faster iteration. These updates are detailed in the ASP.NET Core and MAUI sections.
7. What’s new in Entity Framework Core?
Entity Framework Core in Preview 4 introduces approximate vector search for SQL Server 2025, enabling similarity-based queries (e.g., for AI applications). JSON mapping is now fully integrated into the relational model, allowing seamless storage and querying of JSON data. Temporal period properties can be mapped to CLR properties, improving support for temporal tables. Additionally, dotnet ef now reads default configurations from a dotnet-ef.json file, simplifying project setup. These enhancements make EF Core more powerful for modern data scenarios. See the EF Core updates for more.