Can you build without buildkit enabled? You can disable it in the Docker Engine settings. You should not see this message even with buildkit, but I don’t have better idea right now and if it is a protocol error, it might be related to buildkit. Disabling buildkit doesn’t always help, but if I don’t know the cause of an issue on Windows or Mac where buildkit is enabled, I always recommend to disable it.
I am not surprised since you just renamed your image. If you want to use the getting-started image, you need to pull or run it, not build it.
docker run -d --name getting-started -p 8080:80 docker/getting-started