HTTP and TCP

Long nameShort nameDescription
NoHealthyUpstreamUHNo healthy upstream hosts in upstream cluster in addition to 503 response code.
UpstreamConnectionFailureUFUpstream connection failure in addition to 503 response code.
UpstreamOverflowUOUpstream overflow (circuit breaking ) in addition to 503 response code.
NoRouteFoundNRNo route configured  for a given request in addition to 404 response code or no matching filter chain for a downstream connection.
UpstreamRetryLimitExceededURXThe request was rejected because the upstream retry limit (HTTP)  or maximum connect attempts (TCP)  was reached.
NoClusterFoundNCUpstream cluster not found.
DurationTimeoutDTWhen a request or connection exceeded max_connection_duration  or max_downstream_connection_duration .

HTTP only

Long nameShort nameDescription
DownstreamConnectionTerminationDCDownstream connection termination.
FailedLocalHealthCheckLHLocal service failed health check request  in addition to 503 response code.
UpstreamRequestTimeoutUTUpstream request timeout in addition to 504 response code.
LocalResetLRConnection local reset in addition to 503 response code.
UpstreamRemoteResetURUpstream remote reset in addition to 503 response code.
UpstreamConnectionTerminationUCUpstream connection termination in addition to 503 response code.
DelayInjectedDIThe request processing was delayed for a period specified via fault injection .
FaultInjectedFIThe request was aborted with a response code specified via fault injection .
RateLimitedRLThe request was ratelimited locally by the HTTP rate limit filter  in addition to 429 response code.
UnauthorizedExternalServiceUAEXThe request was denied by the external authorization service.
RateLimitServiceErrorRLSEThe request was rejected because there was an error in rate limit service.
InvalidEnvoyRequestHeadersIHThe request was rejected because it set an invalid value for a strictly-checked header  in addition to 400 response code.
StreamIdleTimeoutSIStream idle timeout in addition to 408 or 504 response code.
DownstreamProtocolErrorDPEThe downstream request had an HTTP protocol error.
UpstreamProtocolErrorUPEThe upstream response had an HTTP protocol error.
UpstreamMaxStreamDurationReachedUMSDRThe upstream request reached max stream duration.
OverloadManagerTerminatedOMOverload Manager terminated the request.
DnsResolutionFailedDFThe request was terminated due to DNS resolution failure.
DropOverloadDOThe request was terminated in addition to 503 response code due to drop_overloads .