nats-io/nats-server · error

processGatewaySubjectUnsub %s

Error message

processGatewaySubjectUnsub %s

What it means

Wraps any error returned by parseUnsubProto when a gateway route-unsub (RUnsub) request cannot be parsed. The gateway readLoop received a subject-unsubscription message from another cluster's gateway and its arguments were malformed (bad account/subject/queue fields), so the message is rejected and the prefixed error propagates back through the gateway protocol handling.

Source

Thrown at server/gateway.go:1936

		remove = false
	}
	if remove {
		c.gw.outsim.Delete(accName)
	}
	return nil
}

// RS- protocol received from the remote after sending messages
// on a subject that it has no interest in (but knows about the
// account). Mark this subject with a "no interest" marker to
// prevent further messages being sent.
// If in modeInterestOnly or for a queue sub, remove from
// the sublist if present.
// <Invoked from outbound connection's readLoop>
func (c *client) processGatewayRUnsub(arg []byte) error {
	_, accName, subject, queue, err := c.parseUnsubProto(arg, true, false)
	if err != nil {
		return fmt.Errorf("processGatewaySubjectUnsub %s", err.Error())
	}

	var (
		e          *outsie
		useSl      bool
		newe       bool
		callUpdate bool
		srv        *Server
		sub        *subscription
	)

	// Possibly execute this on exit after all locks have been released.
	// If callUpdate is true, srv and sub will be not nil.
	defer func() {
		if callUpdate {
			srv.updateInterestForAccountOnGateway(accName, sub, -1)
		}
	}()

View on GitHub (pinned to 3a66a489d2)

Solutions

1. Verify all servers in the cluster run a compatible NATS server version (upgrade/downgrade to match)
2. Check gateway connection peers for non-NATS traffic or protocol corruption (tls misconfig, proxies rewriting bytes)
3. Capture gateway traffic (s.gateway debug/trace logs) to see the malformed message and identify the sending peer
4. If a specific peer is faulty, remove/restart that gateway connection

Example fix

// before
// mixed cluster: server A v2.9, server B v2.2 talking over gateways
// after
// pin all servers to the same NATS server version, e.g. nats-server --cluster nats://... on identical binaries

// Operator-level guard: run all gateway-connected servers on the same NATS version
// and monitor logs for processGatewaySubjectUnsub errors to catch a misbehaving peer early.
if err := srv.WaitForShutdown(...); err != nil { /* inspect log for gateway parse errors */ }

When it happens

Trigger: A remote gateway sends a gateway RUnsub protocol message whose arguments fail parseUnsubProto (wrong number of args, invalid subject, malformed queue name), typically due to protocol mismatch between NATS servers of different versions or a corrupted/garbled inter-cluster connection.

Common situations: Mixed-version NATS clusters where an older/newer server sends gateway messages in a different format; a non-NATS or buggy client connecting on a gateway port; corrupted TCP stream between clustered servers.

Related errors

• processGatewaySubjectSub Parse Error: '%s'
• remote leafnode has same cluster name
• attempted to connect to gateway port
• wrong gateway
• gateway name cannot contain spaces

AI-assisted analysis of nats-io/nats-server@3a66a489d2 (2026-09-02). Data as JSON: /api/errors/c88d2c8403730739. Report an issue: GitHub.