✨ Shield now has support for Avalonia UI

What’s new in .NET 9 Preview 4? All You Need To Know

Jun 4, 2024 | .NET

Overview of .NET 9 Preview 4

Ready to dive deep into the latest from the .NET ecosystem? In this section, we’ll explore what .NET 9 Preview 4 is all about, why it matters, and how it stands apart from its predecessors. There’s a lot of exciting improvements and features coming up!

What is .NET 9 and Why It Matters

.NET 9 is the latest iteration of the popular .NET framework, designed to make development faster, easier, and more robust. It aims to elevate performance, enhance security, and offer new language features that make coding a breeze.

Key Features in .NET 9 Preview 4

The new version introduces a host of new features, including:

  • Enhanced Performance
  • Improved security measures
  • New language features in C#
  • Better support for Blazor

Differences Between .NET 9 and Previous Versions

The enhancements are mainly in performance, cloud-native support, and cross-platform capabilities. Stick around to see how these improvements can transform your development workflow.

New Features in .NET 9 Preview 4

In this section, we’ll uncover all the details of the new features that the new .NET iteration brings to the table. From enhanced performance to improved security measures, there’s a lot to look forward to.

Enhanced Performance

Performance is the key of any good framework. The development team has optimized the runtime and compiler to ensure faster execution times and reduced memory usage. This is perfect for high-performance applications where every millisecond counts.

Improved Security Measures

As cyber threats become increasingly sophisticated, .NET 9 Preview 4 incorporates essential security upgrades to keep your applications safe. These improvements include enhanced encryption protocols, better authentication methods, and more secure coding practices.

New Language Features in C#

C# has always been a developer favorite, and with the new version, it’s even better. You get new language features that simplify code and make it more readable. Here’s a sneak peek:

// Example of new C# language feature in .NET 9

public class Person


    public required string FirstName { get; init; } // 'required' keyword enforces assignment

    public required string LastName { get; init; }


This little code example can eliminate common bugs by ensuring essential properties are always assigned.

Enhanced Support for Blazor

Blazor gets a significant boost in .NET 9 Preview 4. It now offers better performance, more components, and simpler integration with JavaScript libraries. If you’re a web developer, this is a game-changer.

Updates to ASP.NET Core

ASP.NET Core is not left behind either. The latest updates simplify the development of web applications, bringing improved performance, better error handling, and new middleware options.

Development Enhancements

Whether you’re debugging or injecting dependencies, the newest version aims to make your life easier. We’re taking a closer look at the core development enhancements in this section.

Introduction to Hot Reload in .NET 9

Hot Reload is a revolutionary feature that allows you to apply code changes without restarting your application. Do you want to see it in action?

// Example code demonstrating Hot Reload

// Before change

Console.WriteLine("Hello, World!");

// After change

Console.WriteLine("Hello, .NET 9 Preview 4!");

With Hot Reload, you can make this change and see the results instantly, speeding up your development process.

Simplified Dependency Injection

Dependency Injection (DI) has been simplified, reducing boilerplate code. Here’s a quick snippet to illustrate:

public class MyService


    private readonly IMyDependency _myDependency;

    // Constructor injection

    public MyService(IMyDependency myDependency)


        _myDependency = myDependency;



DI is now more intuitive, helping you build more modular and testable applications.

Advanced Debugging Tools

When it comes to debugging, .NET 9 brings advanced tools to the fore. Enhanced diagnostic capabilities include better memory profiling and integrated debugging options.

Improvements in Code Analysis and Diagnostics

Improved code analysis tools ensure that your code is optimized and error-free. These tools not only catch errors but also provide recommendations for better coding practices.

Cloud and Microservices

Next, let’s see how .NET 9 Preview 4 is optimized for cloud-native applications and microservice architectures.

.NET 9 and Cloud-Native Applications

Cloud-native development is simplified with .NET 9 Preview 4. It offers:

  • Seamless cloud integration
  • Improved scalability
  • Effortless deployment

Using these tools, building and deploying cloud-native applications is smoother than ever.

Integrations with Microsoft Azure

One of the biggest benefits of .NET 9 Preview 4 is its deep integration with Microsoft Azure. You can easily deploy .NET 9 applications onto Azure, leveraging features like Azure Functions, Logic Apps, and more.

Docker and Kubernetes Support

Containerization is key for modern applications, and .NET 9 Preview 4 enhances support for Docker and Kubernetes. You can now deploy scalable microservices with ease using these platforms.

Cross-Platform Development

.NET 9 is not just about traditional desktop applications. It’s also about mobile and web. In this section, we’ll explore the cross-platform capabilities of .NET 9 Preview 4.

.NET 9 for Mobile Development

Mobile development gets a boost. The framework supports both Android and iOS, making it easier to build cross-platform mobile apps.

Develop with Xamarin and MAUI Updates

With MAUI (Multi-platform App UI), you can create native apps with a single codebase. Here’s an example:

// Sample MAUI app code

using Microsoft.Maui;

using Microsoft.Maui.Controls;

namespace MyApp


    public class App : Application


        public App()


            MainPage = new MainPage();




This simplifies the mobile development process, allowing you to target multiple platforms with the same code.

Desktop and Web Development Enhancements

Desktop and web development aren’t left behind. .NET 9 Preview 4 introduces new features for WPF and WinForms, along with enhanced web development capabilities.

Compatibility and Migration

Thinking about transitioning to .NET 9? This section covers everything you need to know about compatibility and migration.

Migrating from .NET 6/7/8 to .NET 9

Migrating to .NET 9 is straightforward, thanks to comprehensive documentation and tools designed to ease the process. Make sure to test your application thoroughly to avoid any surprises.

Ensuring Backward Compatibility

It maintains backward compatibility with earlier versions, ensuring that your older projects run smoothly without major modifications.

Breaking Changes and Deprecations

Be aware of breaking changes and deprecated features. These changes could impact your application, so it’s crucial to review the release notes.

Tools and Ecosystem Support

From IDE updates to community tools, .NET 9 Preview 4 comes with a rich ecosystem. Visual Studio is your go-to IDE for .NET development, and it’s been updated for the new version. You’ll find better code suggestions, enhanced debugging tools, and improved performance.

Future Outlook

So what’s next for .NET? This section provides a glimpse into the future, showcasing what’s to come in the final release and beyond.

Expected Improvements in .NET 9 Final Release

While the preview version is already impressive, expect even more refinements in the final release. Performance optimizations, advanced features, and bug fixes are on the horizon.

Roadmap for .NET 10

What’s in the pipeline for .NET 10? The roadmap includes further performance improvements, deeper cloud integration, and enhanced cross-platform support.


.NET 9 Preview 4 is packed with features that can elevate your development workflow. If you’re looking for high performance, enhanced security, and robust tools, this is the framework for you.

Ready to dive in? Head over to the official .NET website, download the preview version, and start exploring the new features today. Whether you’re building desktop apps, web applications, or cloud-native solutions, this latest iteration has something for everyone. So, what are you waiting for? Happy coding!

You May Also Like