When an application is pushed onto Cloud Foundry and the application fails to respond to the TCP health checks, then the application crashes and these status codes are logged in the application logs. Exit code 4 means that the TCP health check failed as the application is not listening on the port assigned to it by Cloud Foundry. Exit code 64 means the application is bound to the port assigned by Cloud Foundry, but has failed the health check after a certain period of time.
You can look for the message Timed out after 1m0s: health check never passed in the application logs. This message can occur when pushing or restarting an application; it indicates your application did not start in the duration specified ...
