An invalid response was received from the upstream server

[MinhDuc010194]

I flow this link to create Kong ingress gateway https://konghq.com/blog/kubernetes-ingress-api-gateway
it works well until I got the last step curl $PROXY_IP/foo i got the message "message": "An invalid response was received from the upstream server" instead of "msg": "Hello from the foo microservice". what happens in this case? do I wrong or missing something?

[fffonion]

Consider it's a duplicate of #7716, will move the discussion in issue.