Brokers list page is thowing an exception when keeping chroot empty

[essame]

Zookeeper connected, but brokers list is empty.

Images attached,

As you can see calling /brokers.json is throwing an exception. Here is heroku server log.

It is worth mentioning that I can see a list of topics, but feed list is always empty as well.

This is the connection string zk.connect=localhost:2181 from /opt/kafka/config/server.properties.