Kafka Connect Sink to Cassandra :: java.lang.VerifyError: Bad return type - cassandra

Question

I'm trying to setup a Kafka Connect Sink to collect data from a topic into a Cassandra Table using the Datastax connector : https://downloads.datastax.com/#akc
Running a standalone worker running directly on the broker, running Kafka 0.10.2.2-1 :
name=dse-sink
connector.class=com.datastax.kafkaconnector.DseSinkConnector
tasks.max=1
datastax-java-driver.advanced.protocol.version = V4
key.converter=org.apache.kafka.connect.storage.StringConverter
value.converter=org.apache.kafka.connect.storage.StringConverter
key.converter.schemas.enable=false
value.converter.schemas.enable=false
internal.key.converter=org.apache.kafka.connect.json.JsonConverter
internal.value.converter=org.apache.kafka.connect.json.JsonConverter
internal.key.converter.schemas.enable=false
internal.value.converter.schemas.enable=false
plugin.path=/usr/share/java/kafka-connect-dse/kafka-connect-dse-1.2.1.jar
topics=connect-test
contactPoints=172.16.0.48
loadBalancing.localDc=datacenter1
port=9042
ignoreErrors=true
topic.connect-test.cdrs.test.mapping= kafkakey=key, value=value
topic.connect-test.cdrs.test.consistencyLevel=LOCAL_QUORUM
But i have the following error :
2019-12-23 16:58:43,165] ERROR Task dse-sink-0 threw an uncaught and unrecoverable exception (org.apache.kafka.connect.runtime.WorkerTask)
java.lang.VerifyError: Bad return type
Exception Details:
Location:
com/fasterxml/jackson/databind/cfg/MapperBuilder.streamFactory()Lcom/fasterxml/jackson/core/TokenStreamFactory; #7: areturn
Reason:
Type 'com/fasterxml/jackson/core/JsonFactory' (current frame, stack[0]) is not assignable to 'com/fasterxml/jackson/core/TokenStreamFactory' (from method signature)
Current Frame:
bci: #7
flags: { }
locals: { 'com/fasterxml/jackson/databind/cfg/MapperBuilder' }
stack: { 'com/fasterxml/jackson/core/JsonFactory' }
Bytecode:
0x0000000: 2ab4 0002 b600 08b0
at com.fasterxml.jackson.databind.json.JsonMapper.builder(JsonMapper.java:114)
at com.datastax.dsbulk.commons.codecs.json.JsonCodecUtils.getObjectMapper(JsonCodecUtils.java:36)
at com.datastax.kafkaconnector.codecs.CodecSettings.init(CodecSettings.java:131)
at com.datastax.kafkaconnector.state.LifeCycleManager.lambda$buildInstanceState$9(LifeCycleManager.java:423)
at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
at java.util.HashMap$ValueSpliterator.forEachRemaining(HashMap.java:1625)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
at com.datastax.kafkaconnector.state.LifeCycleManager.buildInstanceState(LifeCycleManager.java:457)
at com.datastax.kafkaconnector.state.LifeCycleManager.lambda$startTask$0(LifeCycleManager.java:106)
at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1660)
at com.datastax.kafkaconnector.state.LifeCycleManager.startTask(LifeCycleManager.java:101)
at com.datastax.kafkaconnector.DseSinkTask.start(DseSinkTask.java:74)
at org.apache.kafka.connect.runtime.WorkerSinkTask.initializeAndStart(WorkerSinkTask.java:244)
at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:145)
at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:139)
at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:182)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
No additional error on cassandra or Kafka side.
I see active connection on the cassandra node but nothing arrive in the Keyspace.
Any idea why ?

Answer 1

Imho this is a problem caused by use of the JSON internal converters with BigDecimal data (see related SO question). As described in the following blog post, the internal.key.converter and internal.value.converter are deprecated since Kafka 2.0, and shouldn't be explicitly set. Can you comment out all internal. properties & re-try?
P.S. Also see how JSON + Decimal has changed in Kafka 2.4