apache/cassandra · critical · ConfigurationException

Missing directive: partitioner

Error message

Missing directive: partitioner

What it means

DatabaseDescriptor.applyPartitioner() requires cassandra.yaml to name a partitioner class (e.g. Murmur3Partitioner) because every token and row key hash depends on it. A null conf.partitioner is a fatal ConfigurationException; the node cannot start without knowing how to hash partition keys.

Source

Thrown at src/java/org/apache/cassandra/config/DatabaseDescriptor.java:1837

    public static void applyLocator()
    {
        initializationLocator = new Locator(RegistrationStatus.instance,
                                            FBUtilities.getBroadcastAddressAndPort(),
                                            initialLocationProvider);
    }

    // definitely not safe for tools + clients - implicitly instantiates schema
    public static void applyPartitioner()
    {
        applyPartitioner(conf);
    }

    public static void applyPartitioner(Config conf)
    {
        /* Hashing strategy */
        if (conf.partitioner == null)
        {
            throw new ConfigurationException("Missing directive: partitioner", false);
        }
        String name = conf.partitioner;
        try
        {
            name = PARTITIONER.getString(conf.partitioner);
            partitioner = FBUtilities.newPartitioner(name);
        }
        catch (Exception e)
        {
            throw new ConfigurationException("Invalid partitioner class " + name, e);
        }

        partitionerName = partitioner.getClass().getCanonicalName();
    }

    private static Pair<DiskAccessMode, Boolean> resolveCommitLogWriteDiskAccessMode(DiskAccessMode providedDiskAccessMode)
    {
        boolean compressOrEncrypt = getCommitLogCompression() != null || (getEncryptionContext() != null && getEncryptionContext().isEnabled());

View on GitHub (pinned to 88fd0f6a0e)

Solutions

1. Add partitioner: org.apache.cassandra.dht.Murmur3Partitioner to cassandra.yaml (the standard choice)
2. If a tool generates your yaml, ensure the partitioner key is emitted; re-add it if stripped
3. Check that any ${...} substitution in the yaml actually resolves to a non-empty value

Example fix

# before (cassandra.yaml)
# partitioner line missing
# after
partitioner: org.apache.cassandra.dht.Murmur3Partitioner

if (yaml.get("partitioner") == null || String.valueOf(yaml.get("partitioner")).isBlank())
    throw new IllegalStateException("cassandra.yaml must set partitioner, e.g. org.apache.cassandra.dht.Murmur3Partitioner");

try {
    DatabaseDescriptor.applyPartitioner(conf);
} catch (ConfigurationException e) {
    if (e.getMessage().equals("Missing directive: partitioner")) {
        // add partitioner: org.apache.cassandra.dht.Murmur3Partitioner to cassandra.yaml
    } else throw e;
}

When it happens

Trigger: cassandra.yaml omits the partitioner directive or sets partitioner: (empty), so conf.partitioner == null when applyPartitioner runs at startup.

Common situations: Hand-trimmed or auto-generated cassandra.yaml missing the partitioner line; environment variable/config substitution wiping the value; copying a minimal yaml that assumes defaults.

Understand the failure class

Background: "is required", "must be set", "missing required field": configuration validation errors across open-source libraries — this error's family across 36 libraries.

Related errors

• %s has authorization enabled which requires %s to enable aut
• %s requires %s
• %s can't be used with %s
• %s does not support %s
• Failed to instantiate %s

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/14251c296f9d0230. Report an issue: GitHub.