In some cases below error would be raised while starting a BW process which starts with KafkaReceiveMessage activity.
=====
-{ActivityName=KafkaReceiveMessage}.
...
com.tibco.bx.core.faults.BxException: Activity output data validation error. The output data from activity [KafkaReceiveMessage] in process [PROCESS_NAME], module [MODULE_NAME] does not conform to the activity output schema. Value is not a node  Schema=
schema-element({http://www.tibco.com/namespaces/tnt/plugins/receiver+5dc4e68c-55e0-4cd1-8a86-38e0b0c405eb+KafkaReceiverMessageOutput}KafkaReceiverMessageOutput)  {http://www.tibco.com/namespaces/tnt/plugins/receiver+5dc4e68c-55e0-4cd1-8a86-38e0b0c405eb+KafkaReceiverMessageOutput}KafkaReceiverMessageOutput
Sequence
schema-element(topic)  {http://www.w3.org/2001/XMLSchema}string
schema-element(partition)  {http://www.w3.org/2001/XMLSchema}long
schema-element(offset)  {http://www.w3.org/2001/XMLSchema}long
schema-element(key)  {http://www.w3.org/2001/XMLSchema}string
schema-element(message)  {http://www.w3.org/2001/XMLSchema}string
schema-element(headers)  {http://genxdm.org/typed/local-types}bwtype-0
Sequence
schema-element(header)  {http://genxdm.org/typed/local-types}bwtype-1
Sequence
schema-element(key)  {http://www.w3.org/2001/XMLSchema}string
schema-element(value)  {http://www.w3.org/2001/XMLSchema}base64Binary
Sequence
Sequence
Sequence
=====

Two reasons are identified as of now which can lead such kind error:
1. The "Bootstrap Servers" on the Kafka Connection resource is not set properly. For example leaving the default literal value "host:port" instead of giving the actual Kafka broker information.
2. A Kafka consumer property "security.protocol" is added to the KafkaReceiveMessage activity with value SASL_SSL without having Kerberos authentication enabled.

Reasons of error "com.tibco.bx.core.faults.BxException: Activity output data validation error"

All Supported Platforms

1. Check the settings of Kafka Connection resource to make sure all configurations are given proper values.
2. If only SSL is enabled for connecting to the assigned Kafka broker, "security.protocol" property on KafkaReceiveMessage should be set "SSL". If SSL is not used, set "security.protocol" to "PLAINTEXT" or remove the property from KafkaReceiveMessage activity thus the default value "PLAINTEXT" would be used. For more options regarding setting "security.protocol" property, please refer to the Kafka official documentation.

KafkaReceiveMessage, Activity output data validation error