.NET Core 3.0 is here

Microsoft has announced the release of .NET Core 3.0. It includes many improvements, including adding Windows Forms and WPF, adding new JSON APIs, support for ARM64 and improving performance across the board. C# 8 is also part of this release, which includes nullable, async streams, and more patterns. F# 4.7 is included and focused on relaxing syntax and targeting .NET Standard 2.0. You can start updating existing projects to target .NET Core 3.0. The release is compatible with previous versions, making updating easy.

You can download .NET Core 3.0, for Windows, macOS, and Linux:

• .NET Core 3.0 SDK and Runtime
• Snap installer
• Docker images

Visual Studio 2019 16.3 and Visual Studio for Mac 8.3 were also released also and are required an update to use .NET Core 3.0 with Visual Studio. .NET Core 3.0 is part of Visual Studio 2019 16.3. You can just get .NET Core by simply upgrading Visual Studio 2019 16.3.

Hundreds of people were involved in making this release happen, including major contributions from the community.

What you should know about .NET Core 3.0

There are some key improvements and guidance that are important to draw attention to

• .NET Core 3.0 is already battle-tested by being hosted for months at dot.net and on Bing.com. Many other Microsoft teams will soon be deploying large workloads on .NET Core 3.0 in production.
   
• Performance is greatly improved across many components and is described in detail at Performance Improvements in .NET Core 3.0.
   
• C# 8 add async streams, range/index, more patterns, and nullable reference types. Nullable enables you to directly target the flaws in code that lead to NullReferenceException. The lowest layer of the framework libraries has been annotated, so that you know when to expect null.
   
• F# 4.7 focuses on making some thing easier with implicit yield expressions and some syntax relaxations. It also includes support for LangVersion, and ships with nameof and opening of static classes in preview. The F# Core Library now also targets .NET Standard 2.0. You can read more at Announcing F# 4.7.
   
• .NET Standard 2.1 increases the set of types you can use in code that can be used with both .NET Core and Xamarin. .NET Standard 2.1 includes types since .NET Core 2.1.
   
• Windows Desktop apps are now supported with .NET Core, for both Windows Forms and WPF (and open source). The WPF designer is part of Visual Studio 2019 16.3. The Windows Forms designer is still in preview and available as a VSIX download.
   
• .NET Core apps now have executables by default. In past releases, apps needed to be launched via the dotnet command, like dotnet myapp.dll. Apps can now be launched with an app-specific executable, like myapp or ./myapp, depending on the operating system.
   
• High performance JSON APIs have been added, for reader/writer, object model and serialization scenarios. These APIs were built from scratch on top of Span<T> and use UTF8 under the covers instead of UTF16 (like string). These APIs minimize allocations, resulting in faster performance, and much less work for the garbage collector. See The future of JSON in .NET Core 3.0.
   
• The garbage collector uses less memory by default, often a lot less. This improvement is very beneficial for scenarios where many applications are hosted on the same server. The garbage collector has also been updated to make better use of large numbers of cores, on machines with >64 cores.
   
• .NET Core has been hardened for Docker to enable .NET applications to work predictably and efficiently in containers. The garbage collector and thread pool have been updated to work much better when a container has been configured for limited memory or CPU.
   
• .NET Core docker images are smaller, particularly the SDK image.
   
• Raspberry Pi and ARM chips are now supported to enable IoT development, including with the remote Visual Studio debugger. You can deploy apps that listen to sensors, and print messages or images on a display, all using the new GPIO APIs. ASP.NET can be used to expose data as an API or as a site that enables configuring an IoT device.
   
• .NET Core 3.0 is a ‘current’ release and will be superseded by .NET Core 3.1, targeted for November 2019. .NET Core 3.1 will be a long-term supported (LTS) release (supported for at least 3 years). We recommend that you adopt .NET Core 3.0 and then adopt 3.1. It’ll be very easy to upgrade.
   
• .NET Core 2.2 will go EOL on 12/23 as it is now the previous ‘current’ release. See .NET Core support policy.
   
• .NET Core 3.0 will be available with RHEL 8 in the Red Hat Application Streams, after several years of collaboration with Red Hat.
   
• Visual Studio 2019 16.3 is a required update for Visual Studio users on Windows that want to use .NET Core 3.0.
   
• Visual Studio for Mac 8.3 is a required update for Visual Studio for Mac users that want to use .NET Core 3.0.
   
• Visual Studio Code users should just always use the latest version of the C# extension to ensure that the newest scenarios work, including targeting .NET Core 3.0.
   
• Azure App Service deployment of .NET Core 3.0 is currently ongoing.
   
• Azure Dev Ops deployment of .NET Core 3.0 is coming soon. Will update when it is available.

Platform support

.NET Core 3.0 is supported on the following operating systems:

• Alpine: 3.9+
• Debian: 9+
• openSUSE: 42.3+
• Fedora: 26+
• Ubuntu: 16.04+
• RHEL: 6+
• SLES: 12+
• macOS: 10.13+
• Windows Client: 7, 8.1, 10 (1607+)
• Windows Server: 2012 R2 SP1+
• Note: Windows Forms and WPF apps only work on Windows.

Chip support follows:

• x64 on Windows, macOS, and Linux
• x86 on Windows
• ARM32 on Windows and Linux
• ARM64 on Linux (kernel 4.14+)

Note: Please ensure that .NET Core 3.0 ARM64 deployments use Linux kernel 4.14 version or later. For example, Ubuntu 18.04 satisfies this requirement, but 16.04 does not.

.NET Conf 2019 (Day 1)