apache/cassandra · warning

JMX settings in cassandra.yaml or cassandra-env.sh have…

Error message

JMX settings in cassandra.yaml or cassandra-env.sh have been bypassed as the JMX connector server is already initialized. Please refer to cassandra.yaml or cassandra-env.sh for JMX configuration info

What it means

Cassandra logs this warning during daemon setup when it detects that a JMX connector server was already initialized by other means (e.g. a remote connector created by jmxremote system properties handled elsewhere or an attach API agent). It skips applying the JMX settings from cassandra.yaml/cassandra-env.sh, so those configured settings are silently ignored.

Solutions

1. Remove the com.sun.management.jmxremote.* JVM flags so Cassandra applies the JMX settings from cassandra.yaml/cassandra-env.sh
2. Or remove the duplicate JMX settings from cassandra.yaml/cassandra-env.sh and keep only the JVM flags, accepting the bypass
3. Verify with jcmd/JConsole which JMX connector is actually listening and confirm only one source of configuration

Example fix

// before (jvm-server.options)
-Dcom.sun.management.jmxremote.port=7199
-Dcom.sun.management.jmxremote.authenticate=false
// after
# flags removed; JMX configured solely in cassandra-env.sh / cassandra.yaml

// before starting Cassandra, ensure a single JMX config source
String jmxPort = System.getProperty("com.sun.management.jmxremote.port");
if (jmxPort != null && cassandraYamlHasJmxSettings())
    throw new IllegalStateException("JMX configured both via system properties and cassandra.yaml/env");

When it happens

Trigger: The daemon property COM_SUN_MANAGEMENT_JMXREMOTE_PORT is present (JMX remote was activated via com.sun.management.jmxremote.* system properties) and an external JMX connector server is already bound, so maybeInitJmx returns early without applying yaml/env configuration.

Common situations: Operators set both -Dcom.sun.management.jmxremote.port on the JVM command line and JMX settings in cassandra-env.sh/cassandra.yaml; running under a monitoring agent (e.g. Jolokia or attach-based agents) that opens its own JMX connector; copy-pasting legacy JMX flags into jvm-server.options after migrating JMX config into cassandra.yaml.

Understand the failure class

Background: Conflicting config options: "cannot be used together" — configuration validation errors across open-source libraries — this error's family across 162 libraries.

Related errors

• Deprecated
• Disabling compaction by setting min_compaction_threshold or…
• Keyspace count warn threshold should be positive, not
• Not yet initialized, can't load new sstables
• Table count warn threshold should be positive, not

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/103882360464dbc5. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/service/CassandraDaemon.java:184

                String appenderName = metricName.substring(0, separator);
                String metric = metricName.substring(separator + 1); // remove "."
                CassandraMetricsRegistry.Metrics.register(DefaultNameFactory.createMetricName(appenderName, metric, null), meter);
            }
        });
        logger = LoggerFactory.getLogger(CassandraDaemon.class);
    }

    private void maybeInitJmx()
    {
        // If the standard com.sun.management.jmxremote.port property has been set
        // then the JVM agent will have already started up a default JMX connector
        // server. This behaviour is deprecated, but some clients may be relying
        // on it, so log a warning and skip setting up the server with the settings
        // as configured in cassandra.yaml or cassandra-env.sh.
        // See: CASSANDRA-11540 & CASSANDRA-11725
        if (COM_SUN_MANAGEMENT_JMXREMOTE_PORT.isPresent())
        {
            logger.warn("JMX settings in cassandra.yaml or cassandra-env.sh have been bypassed as the JMX connector server is " +
                        "already initialized. Please refer to cassandra.yaml or cassandra-env.sh for JMX configuration info");
            return;
        }

        JAVA_RMI_SERVER_RANDOM_ID.setBoolean(true);

        JMXServerOptions jmxServerOptions = DatabaseDescriptor.getJmxServerOptions();
        if (!jmxServerOptions.enabled)
            return;

        try
        {
            jmxServer = JMXServerUtils.createJMXServer(jmxServerOptions);
        }
        catch (IOException e)
        {
            exitOrFail(1, e.getMessage(), e.getCause());
        }

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