dotnet10-whats-new

name

dotnet10-whats-new

description

Official-docs-derived, complete overview of everything new in .NET 10 (released Nov 11 2025, LTS until Nov 10 2028) for agents trained up to .NET 9. Use when the user asks what's new in .NET 10, .NET 10 features, C# 14 features, .NET 10 runtime/JIT/GC improvements, .NET 10 libraries/BCL APIs, .NET 10 SDK/CLI/tooling, ASP.NET Core 10, EF Core 10, .NET MAUI 10, Windows Forms 10, WPF 10, F# 10, Visual Basic .NET 10, .NET 10 breaking changes, or migrating to .NET 10. This skill is an orchestrator: it routes to area-specific markdown files in this skill folder. Do not use for .NET Framework, .NET 8/9 upgrade paths (use dotnet/skills migrate-dotnet8-to-dotnet9), or greenfield .NET 10 project creation.

What's New in .NET 10 — Agent Reference

Comprehensive, official-documentation-derived reference for .NET 10 (GA: November 11, 2025; LTS, supported until November 10, 2028). Intended for AI agents whose training data ends around .NET 9. Source: Microsoft Learn "What's new in .NET 10" family of articles.

Quick facts

• .NET 10 is the LTS successor to .NET 9. Production apps should plan to move to it.
• .NET 8 and .NET 9 both reach end of support on November 10, 2026 (STS support was extended to 24 months).
• Requires the .NET 10 SDK; ships with C# 14, F# 10, ASP.NET Core 10, EF Core 10, .NET MAUI 10, WinForms/WPF updates.
• Tooling: Visual Studio 2026, C# Dev Kit for VS Code, .NET Conf 2025 sessions.
• Three headline themes: performance (JIT, GC, allocations), AI/cloud-native (Microsoft Agent Framework, vector/embedding support across the stack), security (post-quantum cryptography).

How to use this skill (orchestration)

Answer questions about .NET 10 by reading the matching reference file below, then responding. If a question spans areas, read the relevant files.

Topic	Read this file
C# 14 language features (field, extension members, nameof, spans, lambdas, partial, null-conditional assignment, operators), F# 10, Visual Basic	references/csharp-14.md
Runtime: JIT, loop inversion, devirtualization, stack allocation, escape analysis, AVX10.2, NativeAOT, Arm64 GC	references/runtime.md
Class libraries / BCL: cryptography (PQC), JSON, collections, numerics/tensors, globalization, strings, diagnostics, ZIP, WebSocket, TLS, process management	references/libraries.md
SDK & CLI: file-based apps, dotnet tool exec/dnx, platform-specific tools, MTP, containers, completions, package pruning, CLI schema	references/sdk-tooling.md
ASP.NET Core 10: Blazor, Minimal APIs, OpenAPI 3.1, auth/passkeys, metrics, JSON Patch, misc	references/aspnetcore.md
EF Core 10: SQL Server vectors/JSON, Cosmos full-text/hybrid search, complex types, named query filters, LINQ	references/efcore.md
.NET MAUI 10: controls, XAML source generation, platform features (Android/iOS), SafeArea, diagnostics	references/maui.md
Windows Forms 10: dark mode, async forms, clipboard, ScreenCaptureMode, analyzers	references/winforms.md
WPF 10: Fluent styles, Grid shorthand, MessageBox, clipboard, performance	references/wpf.md
Breaking changes / migration guidance	Point the user to migrate-dotnet9-to-dotnet10 skill in dotnet/skills + https://learn.microsoft.com/dotnet/core/compatibility/breaking-changes

Cross-cutting guidance for the agent

• Default targets: use net10.0 for new projects (or net10.0-android, net10.0-ios, etc. for MAUI).
• Performance claims: JIT/GC gains are workload-dependent; verify with benchmarks rather than asserting absolute numbers.
• Experimental APIs: several features are [Experimental] (e.g., ML-DSA/SLH-DSA under SYSLIB5006, Android CoreCLR) — check the diagnostic ID before recommending for production.
• File-based apps: dotnet run app.cs and dotnet publish app.cs (native AOT by default) are now first-class — prefer them for scripts/tools.
• Migration: when the user's goal is upgrading an existing 9.x project, combine this skill's context with the official breaking-changes list and the migrate-dotnet9-to-dotnet10 agent skill rather than guessing.

Official reference links

• Overview: https://learn.microsoft.com/en-us/dotnet/core/whats-new/dotnet-10/overview
• Runtime: https://learn.microsoft.com/en-us/dotnet/core/whats-new/dotnet-10/runtime
• Libraries: https://learn.microsoft.com/en-us/dotnet/core/whats-new/dotnet-10/libraries
• SDK: https://learn.microsoft.com/en-us/dotnet/core/whats-new/dotnet-10/sdk
• C# 14: https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-14
• ASP.NET Core 10: https://learn.microsoft.com/en-us/aspnet/core/release-notes/aspnetcore-10.0
• EF Core 10: https://learn.microsoft.com/en-us/ef/core/what-is-new/ef-core-10.0/whatsnew
• .NET MAUI 10: https://learn.microsoft.com/en-us/dotnet/maui/whats-new/dotnet-10
• WinForms 10: https://learn.microsoft.com/en-us/dotnet/desktop/winforms/whats-new/net100
• WPF 10: https://learn.microsoft.com/en-us/dotnet/desktop/wpf/whats-new/net100