apache/cassandra · critical · IllegalStateException

Unable to find sufficient sources for streaming range " + tr

Error message

Unable to find sufficient sources for streaming range " + trivialRange + " in keyspace " + keyspace

What it means

RangeFetchMapCalculator.getRangeFetchMapForTrivialRanges() builds the streaming plan for bootstrap/rebuild by mapping each trivial (non-pending, naturally owned) range to a replica source. When no live replica in the local datacenter (and after fallback, the cluster) can serve a range, it throws IllegalStateException: the range cannot be streamed at all.

Source

Thrown at src/java/org/apache/cassandra/dht/RangeFetchMapCalculator.java:183

                // sort with the endpoint having the least number of streams first:
                EndpointsForRange replicas = rangesWithSources.get(trivialRange)
                        .sorted(Comparator.comparingInt(o -> optimisedMap.get(o.endpoint()).size()));
                Replicas.temporaryAssertFull(replicas);
                for (Replica replica : replicas)
                {
                    if (passFilters(replica, localDCCheck))
                    {
                        added = true;
                        // if we pass filters, it means that we don't filter away localhost and we can count it as a source,
                        // see RangeFetchMapCalculator#addEndpoints  and RangeStreamer#getRangeFetchMap
                        if (replica.isSelf())
                            continue; // but don't add localhost to avoid streaming locally
                        fetchMap.put(replica.endpoint(), trivialRange);
                        break;
                    }
                }
                if (!added && !localDCCheck)
                    throw new IllegalStateException("Unable to find sufficient sources for streaming range " + trivialRange + " in keyspace " + keyspace);
                if (!added)
                    logger.info("Using other DC endpoints for streaming for range: {} and keyspace {}", trivialRange, keyspace);
                localDCCheck = false;
            }
        }
        return fetchMap;
    }
    /*
        Return the total number of range vertices in the graph
     */
    private int getTotalRangeVertices(MutableCapacityGraph<Vertex, Integer> graph)
    {
        int count = 0;
        for (Vertex vertex : graph.getVertices())
        {
            if (vertex.isRangeVertex())
            {
                count++;

View on GitHub (pinned to 88fd0f6a0e)

Solutions

1. Bring the required replicas up and rerun bootstrap/rebuild (check `nodetool status` for down nodes)
2. If rebuilding in a new DC, ensure the keyspace uses NetworkTopologyStrategy with an RF > 0 for that DC (ALTER KEYSPACE ... WITH replication = {'class':'NetworkTopologyStrategy','dc1':3,'dc2':3})
3. Relax source filters or use nodetool with the appropriate source DC option (e.g. rebuild -- <source_dc>) so valid sources are considered
4. Run `nodetool cleanup`/repair after fixing replication to ensure data exists somewhere to stream from

Example fix

// before
ALTER KEYSPACE ks WITH replication = {'class':'NetworkTopologyStrategy','dc1':3};
// after
ALTER KEYSPACE ks WITH replication = {'class':'NetworkTopologyStrategy','dc1':3,'dc2':3};

// Before rebuild/bootstrap, confirm sources exist in local DC
KeyspaceMetadata ks = Schema.instance.getKeyspaceMetadata(keyspace);
ReplicationFactor rf = ks.params.replication.asStrategy().getReplicationFactor(dc);
if (rf.allReplicas == 0) throw new IllegalArgumentException("Keyspace " + keyspace + " has no replicas in DC " + dc);

try { streamer.fetch(); } catch (IllegalStateException e) { if (e.getMessage().contains("Unable to find sufficient sources")) { verifyReplicasUp(); fixReplication(); } else throw e; }

When it happens

Trigger: Calling getRangeFetchMap (via RangeStreamer.fetch) during bootstrap/rebuild where a range's replicas are all filtered out (down nodes, source filters, or replicas absent from the local DC and localDCCheck fails).

Common situations: Bootstrapping a new node while required replicas are down; rebuilding a node in a DC that has no replica for the keyspace (NetworkTopologyStrategy missing the DC); RF configured smaller than needed in the source DC; aggressive snitch/endpoint filters excluding all sources.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• Unable to find sufficient sources for streaming range " + ra
• Could not finish join for during replacement
• Cannot alter RF while some endpoints are not in normal state
• Keyspace is already added to fetch map
• Unable to find sufficient sources for streaming range in ke

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/6d953234a0c78166. Report an issue: GitHub.