.NET 9 Preview 4

[jamesmontemagno]

We are pleased to announce the release of .NET 9 Preview 4. This release contains the following Libraries & Runtime improvements:

• UnsafeAccessorAttribute supports generic parameters
• Feature switches with trimming support
• Tokenizer library enhancements
• OpenTelemetry: Make activity linking more flexible
• PDB support for System.Reflection.Emit.PersistedAssemblyBuilder

For details on these new features and more see the Libraries release notes and Runtime release notes

Discuss this release with the .NET team on GitHub Discussions.

You can find detailed release notes for additional features in .NET 9 Preview 4 below:

.NET Data & EF Core

• Enhanced database provider for Azure Cosmos DB for NoSQL
• GroupBy complex types
• Read-only primitive collections
• Full release notes

.NET MAUI

• New Input Keyboards
• Android 15 Beta 1 Support
• NativeAOT improvements for iOS & Mac Catalyst
• Full release notes

Discuss this release with the .NET MAUI team on GitHub Discussions

ASP.NET Core

• Built-in support for OpenAPI document generation
• Introducing HybridCache
• Developer exception page improvements
• Added OverscanCount parameter to QuickGrid
• Add static SSR pages to a globally-interactive Blazor Web app
• Avoid 503's during app recycle in IIS
• Full release notes

Discuss this release with the ASP.NET Core team on GitHub Discussions.

WPF

• Theming improvements – Support for Windows 11 theming for WPF apps
• Hyphen based ligature support
• Full release notes

Get started

To get started with .NET 9, install the .NET 9 SDK.

If you're on Windows using Visual Studio, we recommend installing the latest Visual Studio 2022 preview, or get started with Visual Studio Code and the C# Dev Kit extension.

You can find .NET 9 Preview 4 Installer & Binaries on GitHub.

Team Announcements & Discussions

Discuss this release with the product teams on GitHub through the announcements for this release.

• .NET MAUI
• ASP.NET Core
• Libraries & Runtime

Stay up-to-date with .NET 9

You can stay up-to-date with all the features of .NET 9 with:

• What's new in .NET 9
• What's new in ASP.NET Core
• What's new in .NET MAUI
• What's new in EF Core
• Breaking Changes in .NET 9
• .NET 9 Releases

For .NET 9 previews we are utilizing GitHub Discussions to make announcements. For more information read our discussion.

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