Problem Statement

When a consumer client fails to connect to the Redpanda brokers, sometimes there is insufficient information in the client logs. However, you may sometimes find the following warning message in Redpanda logs.  

kafka - connection_context.cc:432 - Error while processing request from 10.0.1.11:50999 - Unsupported version 12 for fetch AP

Solution

Please check the client library and app to confirm the requested version is correct. One possible issue was  librdkafka v2.6.0 's regression. The fix was https://github.com/confluentinc/librdkafka/pull/4871. 
Please try the fixed version or librdkafka v2.5.x.

Notes

If you have any questions on this notice or need further guidance, please contact customer-success@redpanda.com / support@redpanda.com