Kafka Streams Schema Issue when Branching to Multiple Topics

Question

I have an application which branches to one of 20 topics based on some rules. It has starded failing for below error.

stream-thread [pbel-topic-splitter-bc7189fd-e35c-454d-b5e7-97d5e514dc36-StreamThread-1] Failed to process stream task 0_14 due to the following error:
org.apache.kafka.streams.errors.StreamsException: Exception caught in process. taskId=0_14, processor=KSTREAM-SOURCE-0000000000, topic=com.bns.prm. raw.DETAIL, partition=14, offset=334
        at org.apache.kafka.streams.processor.internals.StreamTask.process(StreamTask.java:367)
        at org.apache.kafka.streams.processor.internals.AssignedStreamsTasks.process(AssignedStreamsTasks.java:104)
        at org.apache.kafka.streams.processor.internals.TaskManager.process(TaskManager.java:413)
        at org.apache.kafka.streams.processor.internals.StreamThread.runOnce(StreamThread.java:862)
        at org.apache.kafka.streams.processor.internals.StreamThread.runLoop(StreamThread.java:777)
        at org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:747)
Caused by: org.apache.kafka.common.errors.SerializationException: Error registering Avro schema: {"type":"record","name":"DETAIL","namespace":"com.        bns.eventlayer.prm.avro","fields":[{"name":"isb_IDENTITY_NUMBER","type":"long"},{"name":"ND_TRAN_ID","type":["null","long"],"default":null},{"name"        :"D nnect.data.Timestamp","logicalType":"timestamp-millis"}}],"connect.name":"com.bns.eventlayer.prm.avro.DETAIL"}
Caused by: io.confluent.kafka.schemaregistry.client.rest.exceptions.RestClientException: Schema being registered is incompatible with an earlier schema; error code: 409
        at io.confluent.kafka.schemaregistry.client.rest.RestService.sendHttpRequest(RestService.java:209)

I compared the 2 schemas and found this subtle difference, not sure if this matters...

Before

{
         "name":"SD_ACH_BATCH_OFFSET_TYP",
         "type":[
            "null",
            "string"
         ],
         "default":null
      }

After

      {
         "name":"SD_SECURITY_LEVEL",
         "type":[
            "null",
            {
               "type":"string",
               "avro.java.string":"String"
            }
         ],
         "default":null
      },

Answer 1

its was my mistake, i had to clear an old schema on error topic . Wrote a program to seek to the offset which always crashed (DLQ), read data of the DLQ and figured out its going to the error topic...