What causes BrokerNotFoundException?

`bootstrap.servers` points at a host/port that resolves but has no broker listening (typo, wrong port, stale address after a cluster move), so Streams' admin probe at startup finds zero reachable brokers. Advertised listeners mismatch: the broker advertises a hostname (e.g. `localhost` or an internal Docker/K8s name) that the Streams client cannot resolve or route to, so the initial metadata connect succeeds but follow-up broker discovery fails. Network/DNS/firewall isolation of a single node: in a multi-instance deployment one host can't reach the brokers (bad DNS, security group, NAT) while the rest start fine. Brokers are simply down / not yet up when the Streams app starts (startup ordering race in compose/orchestrators).

How do I fix BrokerNotFoundException?

Verify connectivity from the failing host with the broker API probe: `kafka-broker-api-versions.sh --bootstrap-server ` — if this hangs/fails, it's network/listeners, not Streams. Fix `advertised.listeners` on the brokers so they advertise an address reachable by clients (not `localhost` for remote clients); align listener/security-protocol maps. Double-check `bootstrap.servers` in the Streams config (real hostnames/IPs, correct port); for containers use the service DNS name, not localhost. On a single failing instance in a healthy cluster, debug that host's DNS/firewall/routing specifically (ping/telnet/nc the brokers); and on old clients (<2.7) where an unreachable first bootstrap entry could stall, upgrade and tune `socket.connection.setup.timeout.ms`.

Is BrokerNotFoundException retriable?

No — BrokerNotFoundException is not retriable. Retrying the same call will not help; the underlying cause must be fixed first.

Kafka Exception `BrokerNotFoundException`

Q: What is BrokerNotFoundException in Kafka?

Indicates that none of the specified BOOTSTRAP_SERVERS_CONFIG brokers could be found.

Q: Is BrokerNotFoundException retriable?

No — BrokerNotFoundException is not retriable. Retrying the same call will not help; the underlying cause must be fixed first.

org.apache.kafka.streams.errors.BrokerNotFoundException

Non-retriable Streams

Indicates that none of the specified BOOTSTRAP_SERVERS_CONFIG brokers could be found.

Common Causes

`bootstrap.servers` points at a host/port that resolves but has no broker listening (typo, wrong port, stale address after a cluster move), so Streams' admin probe at startup finds zero reachable brokers.
Advertised listeners mismatch: the broker advertises a hostname (e.g. `localhost` or an internal Docker/K8s name) that the Streams client cannot resolve or route to, so the initial metadata connect succeeds but follow-up broker discovery fails.
Network/DNS/firewall isolation of a single node: in a multi-instance deployment one host can't reach the brokers (bad DNS, security group, NAT) while the rest start fine.
Brokers are simply down / not yet up when the Streams app starts (startup ordering race in compose/orchestrators).

Solutions

Verify connectivity from the failing host with the broker API probe: `kafka-broker-api-versions.sh --bootstrap-server <host:9092>` — if this hangs/fails, it's network/listeners, not Streams.
Fix `advertised.listeners` on the brokers so they advertise an address reachable by clients (not `localhost` for remote clients); align listener/security-protocol maps.
Double-check `bootstrap.servers` in the Streams config (real hostnames/IPs, correct port); for containers use the service DNS name, not localhost.
On a single failing instance in a healthy cluster, debug that host's DNS/firewall/routing specifically (ping/telnet/nc the brokers); and on old clients (<2.7) where an unreachable first bootstrap entry could stall, upgrade and tune `socket.connection.setup.timeout.ms`.

Example Stack Trace

Exception in thread "main" org.apache.kafka.streams.errors.BrokerNotFoundException: Could not find any available broker.
	at org.apache.kafka.streams.processor.internals.StreamsKafkaClient.ensureOneNodeIsReady(StreamsKafkaClient.java:204)
	at org.apache.kafka.streams.processor.internals.StreamsKafkaClient.getBrokerCompatibility(StreamsKafkaClient.java:281)
	at org.apache.kafka.streams.KafkaStreams.checkBrokerVersionCompatibility(KafkaStreams.java:401)
	at org.apache.kafka.streams.KafkaStreams.<init>(KafkaStreams.java:622)
	at org.apache.kafka.streams.KafkaStreams.<init>(KafkaStreams.java:577)

Diagnostic Commands

kafka-broker-api-versions.sh --bootstrap-server localhost:9092   # confirm a broker actually answers from this host

nc -zv broker1 9092   # raw TCP reachability from the failing instance

getent hosts broker1   # confirm DNS resolves the advertised hostname on this node

Hitting BrokerNotFoundException in production? Conduktor Console gives you real-time visibility into clients, consumer groups, and broker health. Browse every Kafka exception or protocol error code.

Kafka Exception BrokerNotFoundException

Common Causes

Solutions

Example Stack Trace

Diagnostic Commands

Related

Kafka Exception `BrokerNotFoundException`