What causes "No name server address, please set it.{}" in apache/rocketmq?

Set the name server explicitly on the client: producer.setNamesrvAddr("10.0.0.1:9876;10.0.0.2:9876") before start()

apache/rocketmq · critical · MQClientException

NO_NAME_SERVER_EXCEPTION

NO_NAME_SERVER_EXCEPTION

Error message

No name server address, please set it.{}

What it means

MQClientException with responseCode ClientErrorCode.NO_NAME_SERVER_EXCEPTION, thrown by validateNameServerSetting() when the client's remoting layer has an empty/null name server address list. It fires at send time (end of sendDefaultImpl / invokeMessageQueueSelector, after route lookup already failed) to give a clearer reason than 'no route': without a name server, no routes can ever be resolved. Response code lets programmatic handlers distinguish config errors from missing topics.

Source

Thrown at client/src/main/java/org/apache/rocketmq/client/impl/producer/DefaultMQProducerImpl.java:732

        }

        validateNameServerSetting();
        throw new MQClientException("No route info for this topic, " + msg.getTopic(), null);
    }

    public MessageQueue selectOneMessageQueue(final TopicPublishInfo tpInfo, final String lastBrokerName, final boolean resetIndex) {
        return this.mqFaultStrategy.selectOneMessageQueue(tpInfo, lastBrokerName, resetIndex);
    }

    public void updateFaultItem(final String brokerName, final long currentLatency, boolean isolation,
                                boolean reachable) {
        this.mqFaultStrategy.updateFaultItem(brokerName, currentLatency, isolation, reachable);
    }

    private void validateNameServerSetting() throws MQClientException {
        List<String> nsList = this.getMqClientFactory().getMQClientAPIImpl().getNameServerAddressList();
        if (null == nsList || nsList.isEmpty()) {
            throw new MQClientException(
                "No name server address, please set it." + FAQUrl.suggestTodo(FAQUrl.NAME_SERVER_ADDR_NOT_EXIST_URL), null).setResponseCode(ClientErrorCode.NO_NAME_SERVER_EXCEPTION);
        }

    }

    private SendResult sendDefaultImpl(
        Message msg,
        final CommunicationMode communicationMode,
        final SendCallback sendCallback,
        final long timeout
    ) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
        this.makeSureStateOK();
        Validators.checkMessage(msg, this.defaultMQProducer);
        final long invokeID = random.nextLong();
        long beginTimestampFirst = System.currentTimeMillis();
        long beginTimestampPrev = beginTimestampFirst;
        long endTimestamp = beginTimestampFirst;
        TopicPublishInfo topicPublishInfo = this.tryToFindTopicPublishInfo(msg.getTopic());

View on GitHub (pinned to 293f588571)

Solutions

Set the name server explicitly on the client: producer.setNamesrvAddr("10.0.0.1:9876;10.0.0.2:9876") before start()
Or set the system property -Drocketmq.namesrv.addr=... / env NAMESRV_ADDR before the producer is constructed (property is read at client build time)
If using the 5.x gRPC client, set the nameserver for route discovery separately (namesrvAddr on ClientConfiguration) in addition to the gRPC endpoint
Verify at startup: log producer.getClientConfig() name server list and fail fast in your bootstrap if empty

Example fix

// before
DefaultMQProducer p = new DefaultMQProducer("g"); p.start(); p.send(msg); // no ns addr
// after
DefaultMQProducer p = new DefaultMQProducer("g");
p.setNamesrvAddr(System.getenv("NAMESRV_ADDR")); // e.g. 10.0.0.1:9876
p.start();
p.send(msg);

Defensive patterns

Strategy: validation

Validate before calling

 String ns = System.getProperty("rocketmq.namesrv.addr", System.getenv("NAMESRV_ADDR"));
if (Strings.isNullOrEmpty(ns)) {
    throw new ConfigurationException("Set rocketmq.namesrv.addr or NAMESRV_ADDR before starting the producer");
}
DefaultMQProducer p = new DefaultMQProducer(group);
p.setNamesrvAddr(ns);

Try / catch

try {
    producer.send(msg);
} catch (MQClientException e) {
    if (e.getResponseCode() == ClientErrorCode.NO_NAME_SERVER_EXCEPTION) {
        throw new ConfigurationException("RocketMQ name server address missing", e);
    }
    throw e;
}

Prevention

Always call setNamesrvAddr explicitly instead of relying on ambient properties
Add a startup assertion that the client's name server list is non-empty
Inject nameserver config via environment and validate it in the health endpoint
Distinguish NO_NAME_SERVER_EXCEPTION by response code in central error handling

When it happens

Trigger: triggerScenarios

Common situations: commonSituations

Related errors

AI-assisted analysis of apache/rocketmq@293f588571 (2026-08-14). Data as JSON: /api/errors/f70ce675f874303c. Report an issue: GitHub.