[jira] [Created] (KAFKA-12963) Improve error message for Class cast exception

["Rasmus Helbig Hansen (Jira)" <ji...@apache.org>]

Rasmus Helbig Hansen created KAFKA-12963:
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             Summary: Improve error message for Class cast exception
                 Key: KAFKA-12963
                 URL: https://issues.apache.org/jira/browse/KAFKA-12963
             Project: Kafka
          Issue Type: Improvement
          Components: streams
    Affects Versions: 2.7.0
            Reporter: Rasmus Helbig Hansen


After a topology change and starting the application again, we got this type of error message:
{noformat}
[g9z-StreamThread-1] ERROR org.apache.kafka.streams.processor.internals.TaskManager  - stream-thread [g9z-StreamThread-1] Failed to process stream task 1_12 due to the following error:org.apache.kafka.streams.errors.StreamsException: ClassCastException invoking Processor. Do the Processor's input types match the deserialized types? Check the Serde setup and change the default Serdes in StreamConfig or provide correct Serdes via method parameters. Make sure the Processor can accept the deserialized input of type key: org.acme.SomeKey, and value: org.acme.SomeValue.Note that although incorrect Serdes are a common cause of error, the cast exception might have another cause (in user code, for example). For example, if a processor wires in a store, but casts the generics incorrectly, a class cast exception could be raised during processing, but the cause would not be wrong Serdes.       at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:185)    at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forwardInternal(ProcessorContextImpl.java:273)    at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:252)    at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:219)    at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:172)    at org.apache.kafka.streams.kstream.internals.KStreamJoinWindow$KStreamJoinWindowProcessor.process(KStreamJoinWindow.java:55)    at org.apache.kafka.streams.processor.internals.ProcessorAdapter.process(ProcessorAdapter.java:71)    at org.apache.kafka.streams.processor.internals.ProcessorNode.lambda$process$2(ProcessorNode.java:181)    at org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl.maybeMeasureLatency(StreamsMetricsImpl.java:883)    at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:181)    at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forwardInternal(ProcessorContextImpl.java:273)    at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:252)    at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:219)    at org.apache.kafka.streams.processor.internals.SourceNode.process(SourceNode.java:86)    at org.apache.kafka.streams.processor.internals.StreamTask.lambda$process$1(StreamTask.java:703)    at org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl.maybeMeasureLatency(StreamsMetricsImpl.java:883)    at org.apache.kafka.streams.processor.internals.StreamTask.process(StreamTask.java:703)    at org.apache.kafka.streams.processor.internals.TaskManager.process(TaskManager.java:1105)    at org.apache.kafka.streams.processor.internals.StreamThread.runOnce(StreamThread.java:647)    at org.apache.kafka.streams.processor.internals.StreamThread.runLoop(StreamThread.java:553)    at org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:512)Caused by: java.lang.ClassCastException: class org.acme.SomeValue cannot be cast to class org.acme.OtherValue (org.acme.SomeValue and org.acme.OtherValue are in unnamed module of loader 'app')    at org.apache.kafka.streams.kstream.internals.KStreamKStreamJoin$KStreamKStreamJoinProcessor.process(KStreamKStreamJoin.java:112)    at org.apache.kafka.streams.processor.internals.ProcessorAdapter.process(ProcessorAdapter.java:71)    at org.apache.kafka.streams.processor.internals.ProcessorNode.lambda$process$2(ProcessorNode.java:181)    at org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl.maybeMeasureLatency(StreamsMetricsImpl.java:883)    at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:181){noformat}
 It doesn't give enough context, like processor name and topic, which made troubleshooting unnecessary tricky.
 
Very similar to KAFKA-8884 which was fixed in 2.4.0. It seems like a regression.



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