.NET 9 runtime isn’t available (yet) for AWS Codebuild. Even after installing the SDK using the following commands, my build would still get .NET 6 instead: version: 0.2 env: shell: bash phases: install: commands: - curl -L https://dot.net/v1/dotnet-install.sh -o dotnet-install.sh - chmod +x ./dotnet-install.sh - ./dotnet-install.sh –channel 9.0 –install-dir /root/.dotnet/ - dotnet –version - dotnet –info