.NET 9 Preview 6 is Now Available

Last night, Microsoft delivered its sixth preview version of .NET 9 ahead of the platform’s public release. I haven’t been reporting on each of these pre-release milestones, but with my work on the modernization of my .NETpad app, I’ve been paying more attention to .NET 9, as everything I’m doing hinges on this release.

“It’s a great time to check out the latest .NET 9 Preview,” the .NET team writes in the announcement post. “We just shipped our sixth preview release, adding to some great features in the previous previews with major enhancements across the .NET Runtime, SDK, libraries, C#, and frameworks including ASP.NET Core, Blazor, and .NET MAUI.”

.NET impacts so many technologies that it’s getting difficult to keep up with it. The core of it, of course, is the C# language, which is being updated to C# 13 in .NET 9. C# 13 includes several new features, like param collections, improved thread synchronization via a new Lock object, and a lot more. But as noted in the quote above, there are updates across the stack that impact the .NET runtime, SDK, and libraries, and specific .NET-based deliverables like ASP.NET Core, Blazor, .NET MAUI, Entity Framework Core, and more.

For me, .NET 9 is particularly interesting because it’s how and when Microsoft will implement the comeback of the Windows Presentation Foundation (WPF), a .NET-based user interface framework that it first introduced in 2006: With .NET 9, WPF is again a top-tier solution for native Windows app developers, thanks in large part to new support for Windows 11 theming (light and dark modes, modern controls, and so on).

This work has gone well, but I’ve been hoping for updates and, even more important, better documentation about exactly what’s happening. The last update was .NET Preview 4, which Microsoft delivered the week of Build 2024. At that time, it implemented Windows 11 theming and … didn’t really explain it very well. It also delivered a really buggy initial version of a new WPF Gallery app in preview form that shows developers what’s possible.

Unfortunately, there’s nothing new for WPF developers in .NET 9 preview 6. (From what I can see, there was that one drop in May and then nothing since.)

To get started with .NET 9 today, you can install the .NET 9 SDK, which is available for Windows (32-bit and 64-bit), Windows on Arm (Arm64), Linux (several versions), and macOS (Intel and Arm). Developers targeting .NET 9 can do so via the Visual Studio 2022 Preview or Visual Studio Code with the C# Dev Kit extension.