-
Bug
-
Resolution: Done
-
Major
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3.2.1.Final
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None
In order to make your issue reports as actionable as possible, please provide the following information, depending on the issue type.
Bug report
For bug reports, provide this information, please:
What Debezium connector do you use and what version?
Debezium Server 3.2.1.Final (standalone)
What is the connector configuration?
debezium.format.header.schemas.enable=false debezium.format.key.schemas.enable=false debezium.format.value.schemas.enable=false debezium.sink.kafka.producer.bootstrap.servers=******* debezium.sink.kafka.producer.compression.type=zstd debezium.sink.kafka.producer.key.serializer=org.apache.kafka.common.serialization.StringSerializer debezium.sink.kafka.producer.sasl.jaas.config=org.apache.kafka.common.security.scram.ScramLoginModule required username="${DEBEZIUM_SINK_KAFKA_PRODUCER_SASL_USERNAME}" password="${DEBEZIUM_SINK_KAFKA_PRODUCER_SASL_PASSWORD}"; debezium.sink.kafka.producer.sasl.mechanism=SCRAM-SHA-512 debezium.sink.kafka.producer.security.protocol=SASL_SSL debezium.sink.kafka.producer.value.serializer=org.apache.kafka.common.serialization.StringSerializer debezium.sink.type=kafka debezium.source.capture.mode=change_streams_update_full_with_pre_image debezium.source.collection.include.list=.*\.documents debezium.source.connector.class=io.debezium.connector.mongodb.MongoDbConnector debezium.source.mongodb.connection.string=mongodb+srv://*******/?retryWrites=true&w=majority debezium.source.offset.flush.interval.ms=0 debezium.source.offset.storage.file.filename=/debezium/data/offsets.dat debezium.source.snapshot.mode=no_data debezium.source.tombstones.on.delete=true debezium.source.topic.prefix=cdc debezium.transforms.router.regex=(.*)\.documents debezium.transforms.router.replacement=cdc.documents debezium.transforms.router.type=org.apache.kafka.connect.transforms.RegexRouter debezium.transforms=router quarkus.http.port=8080 quarkus.log.console.json=true
What is the captured database version and mode of deployment?
(E.g. on-premises, with a specific cloud provider, etc.)
MongoDB Atlas 8.0.12
Kafka 3.8.x AWS MSK
What behavior do you expect?
An actual error message is logged.
What behavior do you see?
```
class java.lang.String cannot be cast to class [B (java.lang.String and [B are in module java.base of loader 'bootstrap')
```
This is happening while we're trying to log the actual error message:
Do you see the same behaviour using the latest released Debezium version?
(Ideally, also verify with latest Alpha/Beta/CR version)
Same code can be seen on `main`.
Do you have the connector logs, ideally from start till finish?
(You might be asked later to provide DEBUG/TRACE level log)
Only partial:
{
"timestamp": "2025-08-22T11:39:33.83375018Z",
"sequence": 1028,
"loggerClassName": "org.slf4j.impl.Slf4jLogger",
"loggerName": "io.debezium.embedded.async.AsyncEmbeddedEngine",
"level": "ERROR",
"message": "Engine has failed with ",
"threadName": "pool-7-thread-1",
"threadId": 34,
"mdc": {},
"ndc": "",
"hostName": "studio-cdc-79f5b9548d-cd7cc",
"processName": "/usr/lib/jvm/java-21-openjdk-21.0.8.0.9-1.el8.x86_64/bin/java",
"processId": 1,
"exception": {
"refId": 1,
"exceptionType": "java.util.concurrent.ExecutionException",
"message": "io.debezium.DebeziumException: java.lang.ClassCastException: class java.lang.String cannot be cast to class [B (java.lang.String and [B are in module java.base of loader 'bootstrap')",
"frames": [
{ "class": "java.util.concurrent.FutureTask", "method": "report", "line": 122 }
,
{ "class": "java.util.concurrent.FutureTask", "method": "get", "line": 191 }
,
{ "class": "io.debezium.embedded.async.AsyncEmbeddedEngine", "method": "runTasksPolling", "line": 511 }
,
{ "class": "io.debezium.embedded.async.AsyncEmbeddedEngine", "method": "run", "line": 221 }
,
{ "class": "io.debezium.server.DebeziumServer", "method": "lambda$start$1", "line": 182 }
,
{ "class": "java.util.concurrent.ThreadPoolExecutor", "method": "runWorker", "line": 1144 }
,
{ "class": "java.util.concurrent.ThreadPoolExecutor$Worker", "method": "run", "line": 642 }
,
{ "class": "java.lang.Thread", "method": "run", "line": 1583 }
],
"causedBy": {
"exception": {
"refId": 2,
"exceptionType": "io.debezium.DebeziumException",
"message": "java.lang.ClassCastException: class java.lang.String cannot be cast to class [B (java.lang.String and [B are in module java.base of loader 'bootstrap')",
"frames": [
{ "class": "io.debezium.server.kafka.KafkaChangeConsumer", "method": "handleBatch", "line": 117 }
,
{ "class": "io.debezium.embedded.async.ParallelSmtAndConvertBatchProcessor", "method": "processRecords", "line": 56 }
,
{ "class": "io.debezium.embedded.async.AsyncEmbeddedEngine$PollRecords", "method": "doCall", "line": 1222 }
,
{ "class": "io.debezium.embedded.async.AsyncEmbeddedEngine$PollRecords", "method": "doCall", "line": 1202 }
,
{ "class": "io.debezium.embedded.async.RetryingCallable", "method": "call", "line": 47 }
,
{ "class": "java.util.concurrent.FutureTask", "method": "run", "line": 317 }
,
{ "class": "java.util.concurrent.Executors$RunnableAdapter", "method": "call", "line": 572 }
,
{ "class": "java.util.concurrent.FutureTask", "method": "run", "line": 317 }
,
{ "class": "java.util.concurrent.ThreadPoolExecutor", "method": "runWorker", "line": 1144 }
,
{ "class": "java.util.concurrent.ThreadPoolExecutor$Worker", "method": "run", "line": 642 }
,
{ "class": "java.lang.Thread", "method": "run", "line": 1583 }
],
"causedBy": {
"exception": {
"refId": 3,
"exceptionType": "java.lang.ClassCastException",
"message": "class java.lang.String cannot be cast to class [B (java.lang.String and [B are in module java.base of loader 'bootstrap')",
"frames": [
{ "class": "io.debezium.server.kafka.KafkaChangeConsumer", "method": "lambda$handleBatch$0", "line": 107 }
,
{ "class": "org.apache.kafka.clients.producer.KafkaProducer", "method": "doSend", "line": 1108 }
,
{ "class": "org.apache.kafka.clients.producer.KafkaProducer", "method": "send", "line": 993 }
,
{ "class": "io.debezium.server.kafka.KafkaChangeConsumer", "method": "handleBatch", "line": 104 }
,
{ "class": "io.debezium.embedded.async.ParallelSmtAndConvertBatchProcessor", "method": "processRecords", "line": 56 }
,
{ "class": "io.debezium.embedded.async.AsyncEmbeddedEngine$PollRecords", "method": "doCall", "line": 1222 }
,
{ "class": "io.debezium.embedded.async.AsyncEmbeddedEngine$PollRecords", "method": "doCall", "line": 1202 }
,
{ "class": "io.debezium.embedded.async.RetryingCallable", "method": "call", "line": 47 }
,
{ "class": "java.util.concurrent.FutureTask", "method": "run", "line": 317 }
,
{ "class": "java.util.concurrent.Executors$RunnableAdapter", "method": "call", "line": 572 }
,
{ "class": "java.util.concurrent.FutureTask", "method": "run", "line": 317 }
,
{ "class": "java.util.concurrent.ThreadPoolExecutor", "method": "runWorker", "line": 1144 }
,
{ "class": "java.util.concurrent.ThreadPoolExecutor$Worker", "method": "run", "line": 642 }
,
{ "class": "java.lang.Thread", "method": "run", "line": 1583 }
]
}
}
}
}
}
}
How to reproduce the issue using our tutorial deployment?
<Your answer>
