It’s a great time to check out the latest .NET 9 Preview! We just shipped our seventh preview release, adding to some major enhancements across the .NET Runtime, SDK, libraries, C#, ASP.NET Core, Blazor, and .NET MAUI. Check out the full release notes linked below and get started today.
This release contains the following improvements.
Libraries
Removal of BinaryFormatter is complete
Enumerate over ReadOnlySpan<char>.Split() segments
Debug.Assert now reports assert condition, by default.
Compression APIs now use zlib-ng
Guid.CreateVersion7 enables creating GUIDs with a natural sort order
Interlocked.CompareExchange for more types
AES-GCM and ChaChaPoly1305 algorithms enabled for iOS/tvOS/MacCatalyst
Changes to X.509 Certificate Loading
Support for XPS documents from XPS virtual printer
Marking Tensor<T> as Experimental
Full release notes
Runtime
ARM64 SVE Support
Post-Indexed Addressing on ARM64
Strength Reduction in Loops
Object Stack Allocation for Boxes
GC Dynamic Adaptation To Application Sizes
Full release notes
C#
Prioritize better overloads with OverloadResolutionPriority attribute
Full release notes
SDK
Container publishing improvements for insecure registries
More consistent environment variables for container publishing
Introduction of Workload Sets for more control over workloads
Mitigating analyzer mismatch issues aka ‘torn SDK’
Full release notes
ASP.NET Core
SignalR supports trimming and Native AOT
Microsoft.AspNetCore.OpenApi supports trimming and Native AOT
Improvements to transformer registration APIs in Microsoft.AspNetCore.OpenApi
Call ProducesProblem and ProducesValidationProblem on route groups
Construct Problem and ValidationProblem result types with IEnumerable<KeyValuePair<string, object?>> values
OpenIdConnectHandler support for Pushed Authorization Requests (PAR)
Data Protection support for deleting keys
Customize Kestrel named pipe endpoints
Improved Kestrel connection metrics
Opt-out of HTTP metrics on certain endpoints and requests
ExceptionHandlerMiddleware option to choose the status code based on the exception
Full release notes
.NET MAUI
Introduction of HybridWebview
New TitleBar Control and Window.TitleBar for Windows
CollectionView & CarouselView improvements with a new opt-in handler for iOS and Mac Catalyst
Ability to bring a Window to the foregrond with ActivateWindow
BackButtonBehavior OneWay binding mode
BlazorWebView backward compatibility host address
Native Embedding improvements
MainPage is Obsolete
New Handler Disconnect Policy
New ProcessTerminated event on WebView Control
New lifecycle methods for remote notifications on iOS & Mac Catalyst
Xcode Sync for CLI and Visual Studio Code
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. .NET 9 can now be installed directly through the Visual Studio installer starting with Visual Studio 2022 17.12 Preview 1.
You can also use Visual Studio Code and the C# Dev Kit extension with .NET 9.
Team Announcements & Discussions
The team has been making monthly announcements alongside full release notes on the dotnet/core GitHub Discussions and has seen great engagement and feedback from the community. We will continue to post each new release on GitHub, but as we get closer to launch this November alongside .NET Conf 2024 (save the date today!), we wanted to cross-post our release details on the .NET blog.
.NET MAUI
ASP.NET Core
Libraries & Runtime
Source-build
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
Additionally, be sure to subscribe to the GitHub Discussions RSS news feed for all release announcements.
We want your feedback, so head over to the .NET 9 Preview 7 GitHub Discussion to discuss features and give feedback for this release.
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