I don't know if ephemeral_response solves this, but the first thing that comes into my mind is caching an error (webservice doesn't respond in time or whatever). This happened to me some times.
Caching the error is a big problem when you have a system that determines if your code is stable or not and blocks deployments in production to prevent errors.
Caching the error is a big problem when you have a system that determines if your code is stable or not and blocks deployments in production to prevent errors.