Mongo Debezium connector 3.3 throwing error

[Shalvin K]

Hi Debezium Community,

We are migrating our MongoDB Debezium connector from version 2.7 to 3.3 and running into an issue with array fields that contain multiple elements.

The exception we are seeing is:

java.util.concurrent.ExecutionException: io.debezium.DebeziumException: Can't find field: _1 in schema Schema{prod.bloom_orders.order_logs.old_data.test_details:STRUCT}
    at io.debezium.connector.mongodb.transforms.MongoDataConverter.buildStruct(MongoDataConverter.java:665)
    at io.debezium.connector.mongodb.transforms.MongoDataConverter.buildStruct(MongoDataConverter.java:653)
    at io.debezium.connector.mongodb.transforms.MongoDataConverter.buildStruct(MongoDataConverter.java:672)
    at io.debezium.connector.mongodb.transforms.ExtractNewDocumentState.newRecord(ExtractNewDocumentState.java:291)
    at io.debezium.connector.mongodb.transforms.ExtractNewDocumentState.doApply(ExtractNewDocumentState.java:234)
    at io.debezium.transforms.AbstractExtractNewRecordState.apply(AbstractExtractNewRecordState.java:104)

Our config is:

converter.schemas.enable=false
transforms=unwrap
transforms.unwrap.type=io.debezium.connector.mongodb.transforms.ExtractNewDocumentState
transforms.unwrap.delete.handling.mode=rewrite
transforms.unwrap.add.fields=op,source.db,source.collection,source.ts_ms
transforms.unwrap.array.encoding=document

The issue happens only when the array field has more than one element. The schema path in the exception shows old_data.test_details which means it is failing on the before-image of an update or delete event.
The first event had one element in the array, and the second event had two elements, and this crash is coming. 
I have tried running this in both 2.7 and 3.3 with same configs, Debezium 2.7 is working and able to produces events.

Any help or pointers to related issues would be appreciated. Thanks.

[Franklin]

Thanks for the information 

[Franklin]

Alright great