FWIW, you also don't need a UIWindowSceneSessionRoleApplication to use a scene configuration for your CarPlay scene. You can just leave the @main annotation on your SwuiftUI App Scene.

Thanks @Frameworks Engineer, this finally got me up and running. I have to say, the CarPlay programming guide is not very helpful here. I started with a SwiftUI app then tried to add CarPlay integration and started down the scene configuration path, but apparently had my CPTemplateApplicationSceneSessionRoleApplication nested as another role under my UIWindowSceneSessionRoleApplication.

@eskimo see my comment above. I didn't file a bug and I don't know if it's related to what other folks are experiencing, but I'm pretty positive the Dropbox change was the cause for me.

+1. I've been fighting this for a while and assumed I'd already tried unloading it. I think for me the underlying issue was that the "Program" it references was symlinked to a file in my Dropbox, which moved from ~/Library/Dropbox to ~/Library/CloudStorage/Dropbox. I had to delete and re-created the symlink, so I guess maybe something in the system was referencing an inode or something instead of the path.