.NET 9.0 Container Images Now Available

[lbussell]

.NET 9.0 is now generally available.

Go deeper on everything new in this release with the latest documentation for every part of .NET 9:

• What's new in .NET 9: Runtime, Libraries, and SDK
• What's new in C# 13
• What's new in F# 9
• What's new in ASP.NET Core
• What's new in .NET Aspire
• What's new in .NET MAUI
• What's new in EF Core
• What's new in WPF
• What's new in Windows Forms

Operating systems supported at launch

Linux

• Alpine 3.20
• Azure Linux 3.0
• Azure Linux 3.0 distroless
• Debian 12 "Bookworm"
• Ubuntu 24.04 "Noble"
• Ubuntu 24.04 "Noble" Chiseled (distroless)

Windows

• Nano Server LTSC 2019
• Nano Server LTSC 2022
• Windows Server Core LTSC 2019
• Windows Server Core LTSC 2022

New versions of these operating systems will also be added throughout .NET 9's support lifecycle according to the .NET containers supported platforms policy.

Breaking Changes

The breaking changes for .NET 9 containers are listed below. For a comprehensive list, see Breaking changes in .NET 9.

.NET 9 container images no longer install zlib

• .NET containers announcement
• Breaking change documentation

In previous .NET versions, .NET container images installed the latest version of the zlib package from the Linux base image package repositories. In .NET 9, the Runtime contains a statically linked version of zlib-ng. As a result, the .NET Runtime no longer has a package dependency on zlib. In order to reduce .NET container image sizes, .NET 9 container images no longer explicitly install zlib, and no longer update zlib in images where it is already installed from the base Linux image.

.NET Monitor 9 tags are version-only

• .NET containers announcement

The .NET Monitor 9 image offering has been simplified to provide only Azure Linux distroless images. As part of this change, the Ubuntu Chiseled and CBL-Mariner tags have been superseded by version-only tags.

If you reference any of the following tags, remove the distro from the tag when updating to .NET 9:

• 8-cbl-mariner-distroless -> 9
• 8.0-cbl-mariner-distroless -> 9.0
• 8-ubuntu-chiseled -> 9
• 8.0-ubuntu-chiseled -> 9.0

The latest tag has also been updated from Ubuntu Chiseled to Azure Linux for .NET Monitor images. The full tags listing for .NET Monitor images can be found in the .NET Monitor README.

For the .NET Monitor images, both Ubuntu Chiseled and Azure Linux Distroless provided a similar capability set, footprint, and security posture. The .NET Monitor images are intended to be used as appliance images; these images are not intended to be used as base images for derivation and are only intended to be used "as-is". With the public availability of the .NET Azure Linux images last year, the .NET Monitor image offering has been simplified to only produce images based on the Azure Linux distro and the tagging scheme has been simplified to reflect this change.