Hi, Gyula I met a similar situation.
We used flink 1.4 before, and everything is ok. Now, we upgrade to flink 1.7 and use non-legacy mode, there seems something not ok, it all refers to that it is impossible get the jobmanagerGateway at client side. When I create a cluster without a job, I describe the cluster, flink will throw the same exception as you pointed out. When I submit a job, I want to trigger a savepoint at client side, it will also throw the same exception. Don't know why in non-legacy mode,flink will not write back the leader info into zookeeper in the path of /flink/app_99999_000/leader/000000000/job _manager_lock. This causes all the operations fail when using the jobmanagerGateway method in ClusterClient. Hope someone can explain how to do this in a non-legacy mode. Yours sincerely Joshua
