Our API gateway started handing this back to roughly a third of all requests: { "source" : "auth" , "message" : "Upstream Service Unavailable" , "error" : "Upstream Service unreachable" } Restart the gateway and everything is fine. A day later, it's back. No deploy, no code change, no traffic spike, nothing in the backend logs — the backends were healthy the whole time. The cause was one open network socket pointing at a pod that no longer existed. The mechan...