GitHub Actions Failing to Build .NET 9.0 Project

[ZjzMisaka]

Description:
I recently updated my project to target .NET 9.0 after its release. I modified the csproj file to set the TargetFramework to .NET 9.0 and successfully built the project on my local machine. However, after committing the changes, the GitHub Actions workflow fails during the build step with the following error:

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

This suggests that the version of the .NET SDK being used in the GitHub Actions environment does not yet support .NET 9.0.

Questions:

1. Is .NET 9.0 supported in GitHub Actions?
2. Do I need to configure my workflow specifically for .NET 9.0?

Task version:
actions/setup-dotnet@v3

Platform:

• Ubuntu
• macOS
• Windows

Runner type:

• Hosted
• Self-hosted

Repro steps:
https://github.com/ZjzMisaka/PowerThreadPool/blob/main/.github/workflows/test.yml

Expected behavior:
Successfully build

Actual behavior:
Build step with the following error:

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

[hongbo-miao]

I think I got a similar issue.

When I upgrade global.json from

{
  "sdk": {
    "version": "8.0.404",
    "quality": "release"
  }
}

to

{
  "sdk": {
    "version": "9.0.100",
    "quality": "release"
  }
}

I got error in my build:

Unhandled exception: System.Exception: The build host could not be found at '/usr/share/dotnet/sdk/9.0.100/DotnetTools/dotnet-format/BuildHost-net472/Microsoft.CodeAnalysis.Workspaces.MSBuild.BuildHost.exe'
   at Microsoft.CodeAnalysis.MSBuild.BuildHostProcessManager.AssertBuildHostExists(String buildHostPath)
   at Microsoft.CodeAnalysis.MSBuild.BuildHostProcessManager.GetDotNetFrameworkBuildHostPath()
   at Microsoft.CodeAnalysis.MSBuild.BuildHostProcessManager.CreateMonoBuildHostStartInfo()
   at Microsoft.CodeAnalysis.MSBuild.BuildHostProcessManager.GetBuildHostAsync(BuildHostProcessKind buildHostKind, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.BuildHostProcessManager.GetBuildHostWithFallbackAsync(BuildHostProcessKind buildHostKind, String projectOrSolutionFilePath, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.Worker.LoadProjectFileInfosAsync(String projectPath, DiagnosticReportingOptions reportingOptions, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.Worker.LoadProjectInfosFromPathAsync(String projectPath, DiagnosticReportingOptions reportingOptions, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.Worker.LoadAsync(CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.LoadSolutionInfoAsync(String solutionFilePath, IProgress`1 progress, ILogger msbuildLogger, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.LoadSolutionInfoAsync(String solutionFilePath, IProgress`1 progress, ILogger msbuildLogger, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildWorkspace.OpenSolutionAsync(String solutionFilePath, ILogger msbuildLogger, IProgress`1 progress, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Tools.Workspaces.MSBuildWorkspaceLoader.LoadAsync(String solutionOrProjectPath, WorkspaceType workspaceType, String binaryLogPath, Boolean logWorkspaceWarnings, ILogger logger, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Tools.CodeFormatter.OpenMSBuildWorkspaceAsync(String solutionOrProjectPath, WorkspaceType workspaceType, Boolean noRestore, Boolean requiresSemantics, String binaryLogPath, Boolean logWorkspaceWarnings, ILogger logger, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Tools.CodeFormatter.FormatWorkspaceAsync(FormatOptions formatOptions, ILogger logger, CancellationToken cancellationToken, String binaryLogPath)
   at Microsoft.CodeAnalysis.Tools.FormatCommandCommon.FormatAsync(FormatOptions formatOptions, ILogger`1 logger, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Tools.Commands.RootFormatCommand.FormatCommandDefaultHandler.InvokeAsync(ParseResult parseResult, CancellationToken cancellationToken)
   at System.CommandLine.Invocation.InvocationPipeline.InvokeAsync(ParseResult parseResult, CancellationToken cancellationToken)