FIX: Project file does not exist in GitHub actions/setup-dotnet@v4

Publishing apps in GitHub with a workflow

Have you ever set up a GitHub Actions workflow for a .NET project, only to be hit with the dreaded MSB1009: Project file does not exist error when running dotnet publish? Yeah, me too. It’s frustrating, but the fix is easier than you think.

Are you publishing an app with actions/setup-dotnet@v4 in a GitHub workflow? And do you receive the same error as below?

MSBUILD : error MSB1009: Project file does not exist.
Switch: Files/dotnet/myapp
Error: Process completed with exit code 1.

This happens because of compatibility issues in newer versions of the actions/setup-dotnet action. If you’re using @v4, it’s likely causing problems with detecting and setting up your .NET SDK properly.

When running a GitHub Actions workflow with dotnet publish, you might encounter an error like this:

This happens because of compatibility issues in newer versions of the actions/setup-dotnet action. If you’re using @v4, it’s likely causing problems with detecting and setting up your .NET SDK properly.

Let’s just downgrade a version to actions/setup-dotnet@v3!

Instead of using v4, downgrade your workflow to v3: actions/setup-dotnet@v3.

Modify your GitHub Actions YAML file like this:

    - name: Use dotnet sdk 8.x (needed for dotnet commands)
      uses: actions/setup-dotnet@v3
      with:
        dotnet-version: '8.x'

This ensures that GitHub Actions properly sets up the .NET SDK and allows dotnet publish to find your project files.

Why does this work?

The v4 version of actions/setup-dotnet introduced changes that might not fully support certain project setups.

By using v3, you get a more stable and tested environment that works seamlessly with most .NET workflows.