As of October 2, the macOS medium, large, and macos.x86.metal.gen1 resource classes are no longer available. Any jobs specifying these resources will fail with an Invalid resource class error. If your project config doesn’t specify a macOS resource class, jobs will be defaulted to macos.x86.medium.gen2.
You can read more about the available macOS resource classes in our documentation.
macOS Resource EOL
