@syntax_ , It seems to me that your source Kafka is a Confluent Kafka cluster and the producer uses schema registry to source the schema from it. In this case, the KafkaAvroSerializer prepends 5 bytes to every message produced to indicate the id of the schema that was used (in you case, schema id 34). If you try to read this message as a pure Avro payload the deserialization will fail because those 5 bytes are not part of the Avro payload. So, the best way to handle this in NiFi is to also use Schema Registry to deserialize Avro messages. With this, NiFi will get the schema ID from the message 5-byte prefix, use that ID to retrieve the correct schema from Schema Registry and then correctly deserialize the Avro payload. Considering that my guess is correct and you're using a Confluent Schema Registry, you should create a new ConfluentSchemaRegistry controller service and configure it with the details of your Schema Registry. Once this is done, edit the configuration of the Avro Reader controller service and set the following: After you do this, your flow should be able to correctly process the messages that you're reading from Kafka. I read the binary message that you send me with NiFi and loaded the schema in my local schema registry service (making sure it got assigned the right ID 34), and I was able to successfully convert the message from Avro to JSON using a ConvertRecord processor: Cheers, André
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