apache/cassandra · warning

Value for key {} is only present in the right set: {}

Error message

Value for key {} is only present in the right set: {}

What it means

Companion warning of Directory.dumpDiff: it logs keys that exist only in the right-hand directory, i.e. the compared Directory knows about nodes/mappings that the local directory lacks. Like its left-set sibling it is diagnostic logging emitted when two directories that should match do not, typically during CMS initialization verification.

Source

Thrown at src/java/org/apache/cassandra/tcm/membership/Directory.java:952

        {
            logger.warn("Addresses differ: {} != {}", addresses, other.addresses);
            dumpDiff(logger, addresses, other.addresses);
        }
    }

    public static <K, V> void dumpDiff(Logger logger, Map<K, V> l, Map<K, V> r)
    {
        for (K k : Sets.intersection(l.keySet(), r.keySet()))
        {
            V lv = l.get(k);
            V rv = r.get(k);
            if (!Objects.equals(lv, rv))
                logger.warn("Values for key {} differ: {} != {}", k, lv, rv);
        }
        for (K k : Sets.difference(l.keySet(), r.keySet()))
            logger.warn("Value for key {} is only present in the left set: {}", k, l.get(k));
        for (K k : Sets.difference(r.keySet(), l.keySet()))
            logger.warn("Value for key {} is only present in the right set: {}", k, r.get(k));

    }

    public static class RemovedNode implements Comparable<RemovedNode>
    {
        public final Epoch removedIn;
        public final NodeId id;
        public final InetAddressAndPort endpoint;

        public RemovedNode(Epoch removedIn, NodeId id, InetAddressAndPort endpoint)
        {
            this.removedIn = removedIn;
            this.id = id;
            this.endpoint = endpoint;
        }

        public boolean equals(Object object)
        {

View on GitHub (pinned to 88fd0f6a0e)

Solutions

1. Verify network connectivity and let the CMS replicate metadata to the lagging node, then retry the operation
2. Compare the logged entries against nodetool status / cluster membership to find which nodes the local directory is missing
3. If a node is genuinely gone, complete its decommission so the extra directory entries are removed

if (!expectedDirectory.equals(ClusterMetadata.current().directory)) {
    expectedDirectory.dumpDiff(ClusterMetadata.current().directory);
    throw new IllegalStateException("Local metadata is behind; resync before proceeding");
}

When it happens

Trigger: Directory.dumpDiff(this, other) is called after a failed equals() between two Directory instances and the right directory contains entries absent from the left, e.g. the local node's directory is missing entries the initiator has.

Common situations: A joining node has not yet learned about recently added cluster members; the initiator migrated the cluster while this node was down; gossip/TCM replication lag or a partition left the local metadata behind.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• Value for key {} is only present in the left set: {}
• Initiator directory different from our
• In progress sequences differ: {} != {}
• Extensions differ: {} != {}
• CMS Membership differ: {} != {}

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/2f920755a3e2ed46. Report an issue: GitHub.