JMX is not enabled to receive remote connections. Please see

Error message

JMX is not enabled to receive remote connections. Please see jmx_server_options in cassandra.yaml for more info.

What it means

A WARN log (not an exception) from the checkJmxPorts startup check's execute(). When jmx_server_options.remote is false, Cassandra's JMX server only accepts local connections and remote nodetool/monitoring clients will be refused. Cassandra logs this warning at startup so operators explicitly notice remote JMX is off; the else branch logs the remote port when it is enabled.

Source

Thrown at src/java/org/apache/cassandra/service/StartupChecks.java:553

        {
            return "jmx_ports";
        }

        @Override
        public void execute(StartupChecksConfiguration configuration)
        {
            if (configuration.isDisabled(name()))
                return;

            JMXServerOptions jmxServerOptions = DatabaseDescriptor.getJmxServerOptions();
            if (!jmxServerOptions.enabled)
            {
                logger.warn("JMX connection server is not enabled for either local or remote connections. " +
                            "Please see jmx_server_options in cassandra.yaml for more info");
            }
            if (!jmxServerOptions.remote)
            {
                logger.warn("JMX is not enabled to receive remote connections. " +
                            "Please see jmx_server_options in cassandra.yaml for more info.");
            }
            else
            {
                logger.info("JMX is enabled to receive remote connections on port: {}", jmxServerOptions.jmx_port);
            }
        }
    };

    public static final StartupCheck checkJMXProperties = new StartupCheck()
    {
        @Override
        public String name()
        {
            return "jmx_properties";
        }

        @Override

View on GitHub (pinned to 88fd0f6a0e)

Solutions

To allow remote monitoring, set jmx_server_options.remote: true in cassandra.yaml and configure jmx_port plus authentication/SSL, then restart
Keep remote disabled and run monitoring locally (sidecar) or via SSH tunnel to localhost:7199
Confirm the change with the INFO log 'JMX is enabled to receive remote connections on port: <port>' after restart

Example fix

// before (cassandra.yaml)
jmx_server_options:
  enabled: true
  remote: false

// after
jmx_server_options:
  enabled: true
  remote: true
  jmx_port: 7199

Defensive patterns

Strategy: validation

Validate before calling

// Pre-flight: check whether remote JMX is on before planning remote monitoring
import org.apache.cassandra.config.DatabaseDescriptor;
var opts = DatabaseDescriptor.getJmxServerOptions();
if (opts.enabled && !opts.remote)
    System.out.println("WARNING: JMX is local-only; configure remote monitoring via sidecar or enable jmx_server_options.remote");

Prevention

Pair jmx_server_options.remote: true with authentication and SSL (rmi, jmx_encryption options) when enabling remote access
For hardened clusters, prefer local sidecar exporters over opening remote JMX
Verify after restart via the INFO log 'JMX is enabled to receive remote connections on port: <port>'
Keep central-monitoring connectivity tests in deployment pipelines

When it happens

Trigger: checkJmxPorts executes at startup while DatabaseDescriptor.getJmxServerOptions().remote is false — jmx_server_options.remote: false in cassandra.yaml (or enabled-only-local configuration).

Common situations: Security-hardened nodes with local-only JMX; central monitoring (Prometheus JMX exporter remote scrape, remote nodetool) failing to connect; operators migrating from legacy com.sun.management.jmxremote flags to jmx_server_options and losing remote access.

Related errors

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/7b69094c0f50cd72. Report an issue: GitHub.