What is the difference between a timeout and an HTTP 500 response?

A timeout means a participant stopped waiting before it obtained the expected result; it may occur while connecting, sending or waiting for a response. An HTTP 500 is an actual response reporting a server-side failure. Correlate proxy and application logs before retrying a mutation. The absence of a response does not prove that the server performed no work, so use idempotency for operations that must not run twice.