Commit cannot be completed since the group has already rebalanced and assigned the partitions to another member

Question

Hello

We designed a notification application which send emails to users. We used KAFKA for building this applications. Due to below issue users are receiving 100s of emails, As it was retrying 100s of emails are sent. we reduced our max.poll.records from 100 to 50 then to 30. yet its not fixed. And also we have  not configured max.poll.interval.ms, we are using the default one. i am a beginner in KAFKA having hard time resolving this issue.

error trace org.apache.kafka.clients.consumer.CommitFailedException: Commit cannot be completed since the group has already rebalanced and assigned the partitions to another member. This means that the time between subsequent calls to poll() was longer than the configured max.poll.interval.ms, which typically implies that the poll loop is spending too much time message processing. You can address this either by increasing max.poll.interval.ms or by reducing the maximum size of batches returned in poll() with max.poll.records.