Downgrading Kafka
Downgrade each Kafka node one at a time. You can stop each Kafka broker and upgrade the component without downtime if you have enough replication for your topic.
Shut down the current Kafka daemon, switch to the previous version, and start the daemon:
su - kafka -c "/usr/hdp/current/kafka-broker/bin/kafka stop" hdp-select set kafka-broker 2.6.0.3-2041 su - kafka -c "/usr/hdp/current/kafka-broker/bin/kafka start"
su - kafka -c "/usr/hdf/current/kafka-broker/bin/kafka stop" hdf-select set kafka-broker 2.6.0.3-2041 su - kafka -c "/usr/hdf/current/kafka-broker/bin/kafka start"
To verify that the Kafka daemon joined the cluster, create a topic and submit it to Kafka. Send a test message for that topic, and then validate that it was received by a consumer.