Source: .NET 11 Preview 5 is now available! · .NET Team · June 10, 2026
The fifth .NET 11 preview is out with improvements across Runtime, SDK, libraries, ASP.NET Core, MAUI, C#, and EF Core—best read alongside build-security checks, MCP templates, memory-safety prep, and RSC security patches from the same quarter.
Libraries
System.Text.Json adds JSON Lines serialization. LINQ adds full outer joins. Cryptography adds X25519 key agreement. Random adds generic numeric APIs.
Runtime
Faster runtime-async suspension, JIT optimizations, and GC trimming/compaction improvements.
SDK
File-based apps can reference other C# files. Build-time SDK vulnerability and EOL checks. dotnet new MCP Server template. Console apps include System.Net.Http.Json by default.
C#
Closed class hierarchies, union declarations/patterns, and Unsafe Evolution (C# 16 memory safety preview).
ASP.NET Core
Blazor SSR client-side validation, QuickGrid without interactivity, Blazor WebAssembly Gateway, SupplyParameterFromSession.
.NET MAUI
Reliability/platform-fix wave, CancellationToken-aware animations, Windows Maps via Azure Maps, Android API 37 stabilization.
Entity Framework Core
dotnet ef for file-based apps, SQL Server 2022 compatibility default, EF1004 async-sync warning, cleaner query SQL.
Practical takeaway
Try Preview 5 with CI vulnerability checks, MCP template spikes, and EF1004 as warnings-as-errors—not just a feature checklist.