I am using Confluent 3.2 in a set of Docker containers, one of which is running a kafka-connect worker.

For reasons yet unclear to me, two of my four connectors - to be specific, hpgraphsl's MongoDB sink connector - stopped working. I was able to identify the main problem: The connectors did not have any tasks assigned, as could be seen by calling GET /connectors/{my_connector}/status. The other two connectors (of the same type) were not affected and were happily producing output.

I tried three different methods to get my connectors running again via the REST API:

• Pausing and resuming the connectors
• Restarting the connectors
• Deleting and the creating the connector under the same name, using the same config

None of the methods worked. I finally got my connectors working again by:

• Deleting and creating the connector under a different name, say my_connector_v2 instead of my_connector

What is going on here? Why am I not able to restart my existing connector and get it to start an actual task? Is there any stale data on the kafka-connect worker or in some kafka-connect-related topic on the Kafka brokers that needs to be cleaned?

I have filed an issue on the specific connector's github repo, but I feel like this might actually be general bug related to the intrinsics of kafka-connect. Any ideas?