When reading from a collection into a dataframe I get an fatal exception.
I do the following to load the dataframe:
val database: String = "db"
val collection: String = "collection"
val readConfig = ReadConfig(Map("uri" -> ("mongodb://mongo/" + database + "." + collection)))
val sessionDF = spark.read.format("com.mongodb.spark.sql").options(readConfig.asOptions).load()
println(sessionDF.show())

When I run the same code with 2.1.0 connector the dataframe shows up without an exception.

The exception when running:
java.lang.NoSuchMethodError: org.apache.spark.sql.catalyst.analysis.TypeCoercion$.findTightestCommonType()Lscala/Function2;

With trace:
at com.mongodb.spark.sql.MongoInferSchema$.com$mongodb$spark$sql$MongoInferSchema$$compatibleType(MongoInferSchema.scala:135)
at com.mongodb.spark.sql.MongoInferSchema$$anonfun$getCompatibleArraySchema$1.apply(MongoInferSchema.scala:279)
at com.mongodb.spark.sql.MongoInferSchema$$anonfun$getCompatibleArraySchema$1.apply(MongoInferSchema.scala:274)
at scala.collection.IterableLike$class.takeWhile(IterableLike.scala:160)
at scala.collection.AbstractIterable.takeWhile(Iterable.scala:54)
at com.mongodb.spark.sql.MongoInferSchema$.getCompatibleArraySchema(MongoInferSchema.scala:274)
at com.mongodb.spark.sql.MongoInferSchema$.getSchemaFromArray(MongoInferSchema.scala:257)
at com.mongodb.spark.sql.MongoInferSchema$.com$mongodb$spark$sql$MongoInferSchema$$getDataType(MongoInferSchema.scala:227)
at com.mongodb.spark.sql.MongoInferSchema$$anonfun$com$mongodb$spark$sql$MongoInferSchema$$getSchemaFromDocument$1.apply(MongoInferSchema.scala:114)
at com.mongodb.spark.sql.MongoInferSchema$$anonfun$com$mongodb$spark$sql$MongoInferSchema$$getSchemaFromDocument$1.apply(MongoInferSchema.scala:114)
at scala.collection.Iterator$class.foreach(Iterator.scala:893)
at scala.collection.AbstractIterator.foreach(Iterator.scala:1336)
at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
at com.mongodb.spark.sql.MongoInferSchema$.com$mongodb$spark$sql$MongoInferSchema$$getSchemaFromDocument(MongoInferSchema.scala:114)
at com.mongodb.spark.sql.MongoInferSchema$$anonfun$2.apply(MongoInferSchema.scala:78)
at com.mongodb.spark.sql.MongoInferSchema$$anonfun$2.apply(MongoInferSchema.scala:78)
at scala.collection.Iterator$$anon$11.next(Iterator.scala:409)
at scala.collection.Iterator$class.foreach(Iterator.scala:893)
at scala.collection.AbstractIterator.foreach(Iterator.scala:1336)
at scala.collection.TraversableOnce$class.foldLeft(TraversableOnce.scala:157)
at scala.collection.AbstractIterator.foldLeft(Iterator.scala:1336)
at scala.collection.TraversableOnce$class.aggregate(TraversableOnce.scala:214)
at scala.collection.AbstractIterator.aggregate(Iterator.scala:1336)
at org.apache.spark.rdd.RDD$$anonfun$treeAggregate$1$$anonfun$24.apply(RDD.scala:1136)
at org.apache.spark.rdd.RDD$$anonfun$treeAggregate$1$$anonfun$24.apply(RDD.scala:1136)
at org.apache.spark.rdd.RDD$$anonfun$treeAggregate$1$$anonfun$25.apply(RDD.scala:1137)
at org.apache.spark.rdd.RDD$$anonfun$treeAggregate$1$$anonfun$25.apply(RDD.scala:1137)
at org.apache.spark.rdd.RDD$$anonfun$mapPartitions$1$$anonfun$apply$23.apply(RDD.scala:797)
at org.apache.spark.rdd.RDD$$anonfun$mapPartitions$1$$anonfun$apply$23.apply(RDD.scala:797)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:87)
at org.apache.spark.scheduler.Task.run(Task.scala:99)
at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:325)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)