This error is showing that one of your "List" processors is starting and its attempting to migrate the state information from the old way of storing state in the DistributedMapCache, to the new way in the StateManager (ZK or local WAL).
The error is because the processor has a DistributedMapCacheClient configured and the client can't connect to the DistributedMapCacheServer.
If you have state that you believe needs to be migrated, then ensure that the DistributedCachServer is correctly configured and running, and ensure the DistributedCacheClient is configured with the correct host and port for where the server is running.
If you don't have old state that needs to be migrated, just change your "List" processor so that it doesn't use a DistributedMapCacheClient and then it will skip over this migration. The cache client was only required in older versions of NiFi before the internal StateManager was introduced.