title: The following subscribed topics are not assigned to any members
body: <p>I'm still quite new to kafka, and something happened to me which I don't understand. I have 2 apps. One is using SpringKafkas listeners to consumer binary avro messages and process them. For some debugging purposes I wrote trivial second cli app, which take topic, offset brokers etc. to consume it using just plain kafka classes, without spring kafka. Both were working for a while. Recently something went wrong with the server.</p>
  
  <p>Main app now does not consume any messages. During startup is sometimes(!) prints message like: "The following subscribed topics are not assigned to any members ..." When I enable debugging, I see it's spinning on "Leader for partition ... unavailable for fetching offset, wait for metadata refresh". </p>
  
  <p>Ok, I could understand from that, that "something went wrong" with the cluster. What is puzzling me a lot is, that our cli app has no issues whatever to connect to the cluster and prints all messages from beginning of topic. I reverified multiple times, that both apps uses same brokers, same topic, different groupId. Neither app specifies partition id anywhere.</p>
  
  <p>What could be the cause, that one app have no problemm reading from topic, while another is unable to "connect" and consume neither preexisting nor new messages from topic?</p>