Turns out this was a bug in the Phoenix Query Server (technically Apache Avatica): https://issues.apache.org/jira/browse/CALCITE-1458 The author of the Phoenix-Sharp (C# driver) https://github.com/Azure/hdinsight-phoenix-sharp had a similar problem to what you were saying. What happens is that a change in serialization was not made fully backwards compatible and the attribute which the phoenixdb driver was likely expected (I have not verified this) was no longer being serialized over the wire. As such, the server was sending the data back in an attribute the client was not aware existed. I have a fix I'm putting up on CALCITE-1458 shortly which should address the issue without requiring a change in the client. ... View more