Remote client gets connection to localhost refused

Check: advertised.listeners value. Fix: It advertises localhost by design — set your internal address (deploy step 2).

Broker down after reboot

Check: `systemctl status kafka kafka-format`. Fix: kafka-format must succeed once; check /var/lib/kafka ownership (kafka:kafka).

Storage format error on first boot

Check: journalctl -u kafka-format. Fix: If /var/lib/kafka has stale files, clear the volume — format only runs on empty storage.

Troubleshoot Apache Kafka (KRaft, Hardened)

Symptom	Check	Fix
Remote client gets connection to localhost refused	advertised.listeners value	It advertises localhost by design — set your internal address (deploy step 2).
Broker down after reboot	`systemctl status kafka kafka-format`	kafka-format must succeed once; check /var/lib/kafka ownership (kafka:kafka).
Storage format error on first boot	journalctl -u kafka-format	If /var/lib/kafka has stale files, clear the volume — format only runs on empty storage.

Logs & useful commands

/var/log/kafka; `journalctl -u kafka -f`
Health: /opt/kafka/bin/kafka-broker-api-versions.sh --bootstrap-server localhost:9092
First boot state: kafka-format.service generates a fresh KRaft cluster id and formats /var/lib/kafka once (guarded by meta.properties), then kafka.service starts. Broker answers within ~1 minute.

Still stuck? Email support@dcassociatesgroup.com with the product name, cloud + region, instance size, and the output of the health command — first response within 1 business day, most tickets same-day.