ubuntu-latest: Failing to run NET9 app due to missing .NET9 SDK and runtime

[mary-georgiou-sonarsource]

Description

After pointing ubuntu-latest to ubuntu-24.0 image, we started having all our pipeline failing with the error

/usr/lib/dotnet/sdk/8.0.114/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.TargetFrameworkInference.targets(166,5): error NETSDK1045: The current .NET SDK does not support targeting .NET 9.0.  Either target .NET 8.0 or lower, or use a version of the .NET SDK that supports .NET 9.0. Download the .NET SDK from https://aka.ms/dotnet/download [/home/vsts/work/1/s/Tests/TestUtilities/TestUtilities.csproj::TargetFramework=net9.0]

Reason is that ubuntu-latest does not contain .net9.
Could you please add it?

Thanks a lot!

Platforms affected

• Azure DevOps
• GitHub Actions - Standard Runners
• GitHub Actions - Larger Runners

Runner images affected

• Ubuntu 20.04
• Ubuntu 22.04
• Ubuntu 24.04
• macOS 13
• macOS 13 Arm64
• macOS 14
• macOS 14 Arm64
• macOS 15
• macOS 15 Arm64
• Windows Server 2019
• Windows Server 2022
• Windows Server 2025

Image version and build link

Image: ubuntu-24.04
Version: 20250330.1.0
Included Software: https://github.com/actions/runner-images/blob/ubuntu24/20250330.1/images/ubuntu/Ubuntu2404-Readme.md
Image Release: https://github.com/actions/runner-images/releases/tag/ubuntu24%2F20250330.1

Is it regression?

No

Expected behavior

Projects targeting .NET9 successfully build.

Actual behavior

Projects targeting .NET9 fail.

Repro steps

Build any project on Azure with ubuntu-latest runner.

[vidyasagarnimmagaddi]

Hi @mary-georgiou-sonarsource , Thank you for bringing this issue to our attention. We will look into this issue and will update you after investigating.

[viktorz]

I would argue that this is a regression as both previous versions have .net9 installed, but 24.04 came without it and I am not seeing any announcements that manual action will be required for projects targeting .net9 and ubuntu-latest.
May be I have missed the information, but now we have to update tens of pipelines to start with UseDotNet@2 and waste CPU and time on each run.

[hemanthmanga]

Hi All,
We have added the .NET 9 version to both Ubuntu 20 and Ubuntu 22. Kindly check the change. However, for Ubuntu 24, .NET 9 is not yet available in the package manager as it is currently not supported in the built-in Ubuntu feed. If needed, you can install it manually use backports, configure it with setup-dotnet or switch to ubuntu-22.04 instead of ubuntu-latest. For more information, please read the complete documentation. We are closing this issue, Thank you.