I wasted literally two hours on this one, so putting down a note to hopefully help future Googlers. Symptom Here’s all the various errors that I got in the hive-server2.log during my attempts to get a CREATE EXTERNABLE TABLE to work against a MongoDB table in Hive: Caused by: java.lang.ClassNotFoundException: com.mongodb.hadoop.io.BSONWritable Caused by: java.lang.ClassNotFoundException: com.mongodb.util.JSON Caused by: java.lang.ClassNotFoundException: org.bson.conversions.Bson Caused by: java.lang.ClassNotFoundException: org.bson.io.OutputBuffer Whilst Hive would throw errors along the lines of: