nats-io/nats-server · error · JSMirrorConsumerSetupFailedError

invalid consumer create response

Error message

invalid consumer create response

What it means

While (re)creating the mirror consumer, the response received on the reply subscription was not a valid consumer create response (malformed or unexpected payload), so mirror setup fails; the setup loop regenerates the subject and retries the request.

Source

Thrown at server/stream.go:4001

					b, _ := json.Marshal(req)
					// Regenerate subject since the previous name could've been included in it.
					subject = generateSubject()
					// Recreate the reply subscription so we don't get stale responses from other servers.
					mset.unsubscribe(crSub)
					if reply, respCh, crSub, err = newReplySubscription(); err != nil {
						mirror.err = NewJSMirrorConsumerSetupFailedError(err, Unless(err))
						retry = true
						mset.mu.Unlock()
						return
					}
					mset.outq.send(newJSPubMsg(subject, _EMPTY_, reply, nil, b, nil, 0))
					mset.mu.Unlock()
					goto SELECT
				}
				mset.unsubscribe(crSub)
				cerr := ccr.Error
				if cerr == nil {
					cerr = NewJSMirrorConsumerSetupFailedError(errors.New("invalid consumer create response"))
				}
				mset.srv.Warnf("JetStream error response for create mirror consumer: %+v", cerr)
				mirror.err = cerr
				// Let's retry as soon as possible, but we are gated by sourceConsumerRetryThreshold
				retry = true
				mset.mu.Unlock()
				return
			}

			// If using durable sourcing, we need the consumer to use acks based on flow control.
			if durableDeliverSubject != _EMPTY_ && ccr.ConsumerInfo.Config.AckPolicy != AckFlowControl {
				mset.unsubscribe(crSub)
				mirror.err = NewJSMirrorConsumerRequiresAckFCError()
				retry = true
				mset.mu.Unlock()
				return
			}

View on GitHub (pinned to 3a66a489d2)

Solutions

1. Check server logs and network between cluster peers for corrupted or stale replies
2. Allow the automatic retry to succeed once the cluster is stable
3. Restart or recreate the mirror stream if setup keeps failing

When it happens

Trigger: Thrown at server/stream.go:4001 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of nats-io/nats-server@3a66a489d2 (2026-09-02). Data as JSON: /api/errors/edf9dfc0b29cbe9a. Report an issue: GitHub.