Ubuntu 26.04 (Resolute Raccoon) has officially launched, and for .NET developers, this release brings exciting enhancements and seamless integration. Canonical and Microsoft have collaborated to ensure .NET 10 ships as the default LTS version, with extended support for .NET 8 and 9 via additional feeds. This article covers everything you need to know—from installation and container images to security improvements and testing workflows. Whether you're building new apps or migrating existing ones, these changes streamline development on Ubuntu's latest LTS. Let's dive into the ten most important updates for .NET on Ubuntu 26.04.
1. .NET 10 Is the Default LTS
Ubuntu 26.04 comes pre-bundled with .NET 10, the latest long-term support release. This means you can start developing and running .NET applications immediately after a fresh OS install or by running a simple apt install dotnet-sdk-10.0 command. Canonical and Microsoft have worked closely to guarantee stable performance and full compatibility, making this the go-to environment for enterprise .NET workloads. If you need older versions, .NET 8 and 9 are also available through a separate PPA, ensuring backward compatibility without sacrificing the benefits of the new LTS.
2. Quick Installation via APT
Installing .NET 10 on Ubuntu 26.04 is as straightforward as updating your package list and running one command. Begin with sudo apt update, then install the SDK with sudo apt install dotnet-sdk-10.0. This method uses the official Ubuntu repositories, so you get automatic updates and seamless integration with system libraries. For those testing in containers, you can replicate the same steps inside an ubuntu:resolute image. The installation is optimized for both development and production, with no extra configuration required.
3. New Container Images with the Resolute Tag
Container images for .NET 10+ are now available under the resolute tag. If you previously used noble tags, simply update them to resolute to upgrade to Ubuntu 26.04. These images include the same flavor options as before, including chiseled variants for smaller attack surfaces. Note that containers share the host kernel—so running a 26.04 container on a 24.04 host will still use the host's kernel. This compatibility ensures smooth transitions without disrupting existing containerized .NET applications.
4. Linux Kernel 7.0 on the Horizon
Ubuntu 26.04 release notes highlight Linux 7.0 as a major change. Microsoft's .NET team plans to begin testing on this kernel once Ubuntu 26.04 VMs are available in their lab. While not yet supported in the initial release, this upcoming kernel promises performance improvements and new hardware features. Developers can expect .NET to fully leverage Linux 7.0 optimizations in future updates, ensuring apps run faster and more efficiently on modern hardware.
5. Post-Quantum Cryptography Support
Security takes a leap forward with post-quantum cryptography support, already integrated into .NET 10. Ubuntu 26.04 includes necessary infrastructure for these quantum‑resistant algorithms. While still in early stages, this prepares your applications for a future where classical encryption may be vulnerable. Microsoft and Canonical are committed to making .NET a secure environment, and this addition ensures that your data remains protected against emerging threats.
6. Removal of cgroup v1 (Container Impact)
Ubuntu 26.04 removes support for cgroup v1, fully migrating to cgroup v2. .NET added cgroup v2 support years ago, so this change is expected to be seamless for containerized applications. However, if you rely on legacy monitoring or resource‑control tools that only work with v1, you’ll need to update them. The .NET runtime automatically adapts to the host’s cgroup version, ensuring no disruption in performance or resource tracking for your apps.
7. The Long Road to LTS: CI Testing Since Early 2025
Microsoft’s .NET team began preparing for Ubuntu 26.04 long before its release. Testing on Debian 13 and Ubuntu 24.10 started in early 2025, followed by Ubuntu 26.04 container images in late 2025. Every pull request in the dotnet/runtime repository now runs validation on Ubuntu 26.04, making it one of the most heavily tested OS targets. This rigorous continuous integration ensures that any compatibility issues are caught early, giving developers a rock‑solid platform on day one.
8. Running C# in the Shell (Unix-Style)
A fun revelation from the announcement: you can run C# code directly from the command line using heredocs and stdin. For example, dotnet run - << 'EOF' ... EOF creates a temporary app that prints system info. This pattern, common among AI agents for Python, works just as well with C#. It’s a great way to test small snippets or quickly run scripts without setting up a full project. The example outputs “Hello Ubuntu Resolute Raccoon from .NET 10.0.5” – a testament to the tight integration.
9. No Changes to Container Image Flavors
The new resolute images maintain the same variety as the previous noble ones, including standard, aspnet, and chiseled variants. Chiseled images remain an excellent choice for minimizing attack surface and container size. If you already have Dockerfiles targeting noble, you can migrate to resolute by simply changing the base image tag. The underlying .NET SDK and runtime versions stay consistent, so your application code doesn’t need modifications.
10. Sample Migration: aspnetapp on Chiseled
To demonstrate compatibility, the team shows how to run an ASP.NET Core sample app on a chiseled container from Ubuntu 26.04. You can migrate by updating the base image reference in your Dockerfile. For example, replace FROM mcr.microsoft.com/dotnet/aspnet:10.0-noble with :10.0-resolute. Then rebuild and test. This straightforward update ensures your containerized .NET apps benefit from the latest OS improvements with minimal effort.
In summary, Ubuntu 26.04 empowers .NET developers with a seamless upgrade path, enhanced security, and future-ready infrastructure. From the default .NET 10 LTS and simple installation to post‑quantum cryptography and container modernization, each change reinforces Ubuntu's role as a premier platform for .NET development. Start exploring today—update your environments and take advantage of everything Resolute Raccoon has to offer.