JdbcSinkConnector | WARNING (0/1 Tasks Running)

  • I’m running Kafka Connect (“connect-avro-distributed.properties”) on a separate machine from my Broker. I have Kafka Connect, Schema Registry, KSQLDB & CLI up and running. And, I can see that the Broker has added it to the group.

  • After updating my worker I see that it has been created in Connect, no errors.

  • No errors in my Schema Registry interface (CLI)

However, when I “show connectors;” in KSQL (CLI), I get the following:

sink-jdbc-mysql-01 | SINK | io.confluent.connect.jdbc.JdbcSinkConnector | WARNING (0/1 Tasks Running)

  • I checked out a couple tutorials that had me double check that my drivers are placed in the proper directory… I checked and they are loading in the Kafka Connect window during start-up.

  • There are no other Connectors running in the environment.

I’m not sure at this point what to look for in the configs or driver locations.

Thank you for your help.

Check the Kafka Connect worker logs for errors from the connector.

See: https://developer.confluent.io/learn-kafka/kafka-connect/troubleshooting-kafka-connect/

@rmoff Thank you for pointing me to the tutorials.

Taking a look at the logs, there are a number of WARN messages (see below) and one (1) ERROR. The error is the following:

ERROR Failed to start task sink-jdbc-mysql-01-0 (org.apache.kafka.connect.runtime.Worker:560) java.lang.NoClassDefFoundError: io/confluent/common/config/AbstractConfig

So, I did four (4) things:

  • I searched for where the AbstractConfig class is located (common.config-4.0.3.jar)
  • I located the jar in the directory and double checked that it is in the “plugin.path” config of the properties file.
  • I searched the worker log to see if it loaded during start up, and yes it is.
  • Lastly, I made sure the jar has no access restrictions.

It’s still throwing the same error. Any thoughts?

Other than that…

A series of WARN messages report that 18 different configurations were “supplied but isn’t a known config.” This occurs numerous times during the startup of the worker. The main difference between them is “AdminClientConfig”, “ConsumerConfig”, and “ProducerConfig”.

WARN The configuration ‘config_name’ was supplied but isn’t a known config.



WARN The configuration ‘config_name’ was supplied but isn’t a known config. (org.apache.kafka.clients.consumer.ConsumerConfig:380)



WARN The configuration ‘config_name’ was supplied but isn’t a known config.(org.apache.kafka.clients.consumer.ProducerConfig:380)



How are you running Kafka Connect? Often this error comes from an installation issue.


I was running an Apache Kafka 2.13-2.8.0 install. I went ahead and performed a fresh install of the latest Confluent Community, and the latest connectors. That did the trick.

I think the root of the problem was that the Schema Registry installation was performed later after the Apache Kafka install. In the process, something wasn’t right.

Thank you for your help.

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