We’ve just run in to similar after updating to 8.3.4. We are returning a dataset from a named query, and then writing that dataset straight to a tag. I suspect it is a similar issue to the one in this thread, but just wanted to make sure it was captured, are you able to confirm this will also be resolved in 8.3.5?
Caused by: com.inductiveautomation.ignition.common.model.exception.ProtobufSerializationException: Class 'com.inductiveautomation.ignition.gateway.datasource.BasicStreamingDataset' and object 'Dataset [20R ⅹ 25C]' cannot be Protobuf serialized
at com.inductiveautomation.metro.impl.protoserializers.AnyObjectSerializer.toProtobufMessage(AnyObjectSerializer.java:63)
at com.inductiveautomation.ignition.gateway.gan.protoserializers.QualifiedValueSerializer.toProtobufMessage(QualifiedValueSerializer.java:37)
at com.inductiveautomation.ignition.gateway.gan.protoserializers.QualifiedValueSerializer.toProtobufMessage(QualifiedValueSerializer.java:18)
at com.inductiveautomation.metro.impl.protoserializers.ProtobufUtil.packAnyToList(ProtobufUtil.java:190)
at com.inductiveautomation.metro.impl.protoserializers.generic.collection.ListSerializer.toProtobufMessage(ListSerializer.java:46)
at com.inductiveautomation.metro.impl.protoserializers.generic.collection.ListSerializer.toProtobufMessage(ListSerializer.java:21)
at com.inductiveautomation.metro.impl.protoserializers.AnyArgSerializeBuilder.build(AnyArgSerializeBuilder.java:168)
at com.inductiveautomation.metro.impl.protoserializers.ServiceInvocationSerializer.toProtobufMessage(ServiceInvocationSerializer.java:41)
at com.inductiveautomation.metro.impl.protoserializers.ServiceInvocationSerializer.toProtobufMessage(ServiceInvocationSerializer.java:15)
at com.inductiveautomation.metro.impl.protoserializers.ServerMessageSerializer.toProtobufMessage(ServerMessageSerializer.java:47)
at com.inductiveautomation.metro.impl.transport.ProtobufDirectAdapter.adaptData(ProtobufDirectAdapter.java:79)
at com.inductiveautomation.metro.impl.transport.ProtobufDirectAdapter.adaptData(ProtobufDirectAdapter.java:29)
at com.inductiveautomation.metro.impl.transport.AbstractTransportAdapter.handle(AbstractTransportAdapter.java:59)
at com.inductiveautomation.metro.impl.MessageSendManager.sendNext(MessageSendManager.java:232)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
at java.base/java.util.concurrent.FutureTask.run(Unknown Source)
... 3 common frames omitted
Managed to resolve bu wrapping the return from the named query in a system.dataset.toPyDataSet()