# Ksqldb table key and value with avro schema serialization error **URL:** \ **Category:** ksqlDB\ **Created:** [7 March 2025 17:51 UTC](https://forum.confluent.io/t/ksqldb-table-key-and-value-with-avro-schema-serialization-error/37434 "2025-03-07T17:51:38Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![NikkiZ](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.confluent.io/nikkiz/32/4996_2.png) [@NikkiZ](https://forum.confluent.io/u/NikkiZ)\ **Post date:** [7 March 2025 17:51 UTC](https://forum.confluent.io/t/ksqldb-table-key-and-value-with-avro-schema-serialization-error/37434/1 "2025-03-07T17:51:38Z")
Hi, I created a topic and register Avro schema for the Key and Value. They are both objects. I also verified the schema is registed in the schema registery. Then create a source table in the Ksqldb with below query to pull the data in the .Net. The reason I have to specify the schema id is because I need the property name stay CamelCase as it is defined in the topic. CREATE source TABLE `ExampleTopic` WITH (KAFKA\_TOPIC=‘ExampleTopic’, KEY\_FORMAT=‘Avro’, VALUE\_FORMAT=‘Avro’, KEY\_SCHEMA\_ID=‘1’,VALUE\_SCHEMA\_ID=‘2’); Afetr I push the message to the topic, I get below serialization error when I try select \* from `ExampleTopic`; It all works fine if I don’t specify the KEY\_SCHEMA\_ID and VALUE\_SCHEMA\_ID. However, all the table property name will be upper case. I need to keep them CamelCase. I appriciate any help. Thank you. Here is the error: at org.apache.kafka.streams.processor.internals.AbstractReadWriteDecorator$KeyValueStoreReadWriteDecorator.put(AbstractReadWriteDecorator.java:127) at org.apache.kafka.streams.kstream.internals.KTableTransformValues$KTableTransformValuesProcessor.process(KTableTransformValues.java:124) at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:157) at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forwardInternal(ProcessorContextImpl.java:290) at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:269) at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:228) at org.apache.kafka.streams.kstream.internals.KTableSource$KTableSourceProcessor.process(KTableSource.java:152) at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:157) at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forwardInternal(ProcessorContextImpl.java:290) at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:269) at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:228) at org.apache.kafka.streams.processor.internals.SourceNode.process(SourceNode.java:84) at org.apache.kafka.streams.processor.internals.StreamTask.lambda$doProcess$1(StreamTask.java:793) at org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl.maybeMeasureLatency(StreamsMetricsImpl.java:872) at org.apache.kafka.streams.processor.internals.StreamTask.doProcess(StreamTask.java:793) at org.apache.kafka.streams.processor.internals.StreamTask.process(StreamTask.java:724) at org.apache.kafka.streams.processor.internals.TaskExecutor.processTask(TaskExecutor.java:100) at org.apache.kafka.streams.processor.internals.TaskExecutor.process(TaskExecutor.java:81) at org.apache.kafka.streams.processor.internals.TaskManager.process(TaskManager.java:1182) at org.apache.kafka.streams.processor.internals.StreamThread.runOnce(StreamThread.java:768) at org.apache.kafka.streams.processor.internals.StreamThread.runLoop(StreamThread.java:588) at org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:550) Caused by: org.apache.kafka.connect.errors.DataException: Failed to serialize Avro data from topic \_confluent-ksql-ksqldb-server\_transient\_transient\_ExampleTopic\_3196606156607934861\_1741290716040-KsqlTopic-Reduce-changelog : at io.confluent.connect.avro.AvroConverter.fromConnectData(AvroConverter.java:93) at io.confluent.ksql.serde.connect.KsqlConnectSerializer.serialize(KsqlConnectSerializer.java:53) … 32 more Caused by: org.apache.kafka.common.errors.SerializationException: Error retrieving schema ID{“type”:“record”,“name”:“XXX”,“namespace”:“XXX”,“fields”:[{“name”:“XXX”,“type”:“string”},{“name”:“XXX”,“type”:“string”}]} at io.confluent.kafka.serializers.AbstractKafkaSchemaSerDe.toKafkaException(AbstractKafkaSchemaSerDe.java:253) at io.confluent.kafka.serializers.AbstractKafkaAvroSerializer.serializeImpl(AbstractKafkaAvroSerializer.java:168) at io.confluent.connect.avro.AvroConverter$Serializer.serialize(AvroConverter.java:153) at io.confluent.connect.avro.AvroConverter.fromConnectData(AvroConverter.java:86) … 33 more Caused by: io.confluent.kafka.schemaregistry.client.rest.exceptions.RestClientException: Subject ‘\_confluent-ksql-ksqldb-server\_transient\_transient\_ExampleTopic\_3196606156607934861\_1741290716040-KsqlTopic-Reduce-changelog-key’ not found.; error code: 40401 at io.confluent.kafka.schemaregistry.client.rest.RestService.sendHttpRequest(RestService.java:302) at io.confluent.kafka.schemaregistry.client.rest.RestService.httpRequest(RestService.java:372) at io.confluent.kafka.schemaregistry.client.rest.RestService.lookUpSubjectVersion(RestService.java:463) at io.confluent.kafka.schemaregistry.client.rest.RestService.lookUpSubjectVersion(RestService.java:448) at io.confluent.kafka.schemaregistry.client.CachedSchemaRegistryClient.getIdFromRegistry(CachedSchemaRegistryClient.java:350) at io.confluent.kafka.schemaregistry.client.CachedSchemaRegistryClient.getId(CachedSchemaRegistryClient.java:565) at io.confluent.kafka.schemaregistry.client.CachedSchemaRegistryClient.getId(CachedSchemaRegistryClient.java:545) at io.confluent.kafka.serializers.AbstractKafkaAvroSerializer.serializeImpl(AbstractKafkaAvroSerializer.java:130) … 35 more ---
**Author:** ![system](https://us1.discourse-cdn.com/flex019/uploads/confluentcommunity/original/1X/c49438c90c9df282e9996fdf6971be890c71b65a.svg) [@system](https://forum.confluent.io/u/system)\ **Post date:** [6 April 2025 17:51 UTC](https://forum.confluent.io/t/ksqldb-table-key-and-value-with-avro-schema-serialization-error/37434/2 "2025-04-06T17:51:41Z")
This topic was automatically closed after 30 days. New replies are no longer allowed.