WARN in Lenses Logs “Could not retrieve connectors”

Apache Kafka Connectors
1

In the Lenses logs, there are prominent WARN messages regarding the connectors, indicating that it couldn’t find a class implementing the connector. What does this mean, and how can it be resolved? I’ve included a snippet of the error message, but it essentially repeats the same fields and displays the names of other connectors.

WARN  [i.l.c.c.ConnectorWatcher$] [ioapp-compute-8] Could not retrieve connectors
io.lenses.core.connect.client.ConnectorError: Failed to find any class that implements Connector and which name matches 
org.apache.kafka.connect.file.FileStreamSourceConnector, available connectors are: 
PluginDesc{klass=class com.couchbase.connect.kafka.CouchbaseSinkConnector, 
name='com.couchbase.connect.kafka.CouchbaseSinkConnector', version='4.1.9', encodedVersion=4.1.9, type=sink, typeName='sink', 
location='file:/var/run/connect/connectors/third-party/kafka-connect-couchbase/'}, 
PluginDesc{klass=class com.couchbase.connect.kafka.CouchbaseSourceConnector, 
name='com.couchbase.connect.kafka.CouchbaseSourceConnector', version='4.1.9', encodedVersion=4.1.9, type=source, typeName='source', 
location='file:/var/run/connect/connectors/third-party/kafka-connect-couchbase/'}, 
PluginDesc{klass=class com.datamountaineer.streamreactor.connect.azure.documentdb.sink.DocumentDbSinkConnector, 
name='com.datamountaineer.streamreactor.connect.azure.documentdb.sink.DocumentDbSinkConnector', version='5.0.1'....
2

Hello Edward_k,

This message indicates that you Kafka-connect attempted to find a class used in your connector but couldn’t find it. In this case, the class is: org.apache.kafka.connect.file.FileStreamSourceConnector. If you have multiple connectors activated in Lenses, this issue might go unnoticed. In such cases, you need to delete the problematic connector using the following command:

curl -X DELETE http://kafka-connect.url:8083/connectors/<connector-name>

Afterwards, recreate it, ensuring that the libraries used by the connector actually exist in your Kafka Connect installation and are also in the correct version.

1 Like