predictionIO UR template pio train throws exception Job aborted due to stage failure
<p>I've started to gather events in the production enviroment. After around 100000 events, I tried to run a pio train. It throws an exception and stops.
During the tests the the pio train worked, so I assume the problem is with the events. But the exception message doesn't help.</p>

<pre><code>[INFO] [URModel] Ready to pass date fields names to closure Some(List(, , expireDate))
[INFO] [URModel] Converting PropertyMap into Elasticsearch style rdd
[ERROR] [Executor] Exception in task 0.0 in stage 51.0 (TID 36)
[WARN] [ThrowableSerializationWrapper] Task exception could not be deserialized
[ERROR] [TaskResultGetter] Could not deserialize TaskEndReason: ClassNotFound with classloader org.apache.spark.util.MutableURLClassLoader@6465e468
[WARN] [TaskSetManager] Lost task 0.0 in stage 51.0 (TID 36, localhost): UnknownReason
[ERROR] [TaskSetManager] Task 0 in stage 51.0 failed 1 times; aborting job
Exception in thread "main" org.apache.spark.SparkException: Job aborted due to stage failure: Task 0 in stage 51.0 failed 1 times, most recent failure: Lost task 0.0 in stage 51.0 (TID 36, localhost): UnknownReason
Driver stacktrace:
    at org.apache.spark.scheduler.DAGScheduler.org$apache$spark$scheduler$DAGScheduler$$failJobAndIndependentStages(DAGScheduler.scala:1283)
    at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1271)
    at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1270)
    at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
    at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47)
    at org.apache.spark.scheduler.DAGScheduler.abortStage(DAGScheduler.scala:1270)
    at org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:697)
    at org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:697)
    at scala.Option.foreach(Option.scala:236)
    at org.apache.spark.scheduler.DAGScheduler.handleTaskSetFailed(DAGScheduler.scala:697)
    at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.doOnReceive(DAGScheduler.scala:1496)
    at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1458)
    at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1447)
    at org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:48)
    at org.apache.spark.scheduler.DAGScheduler.runJob(DAGScheduler.scala:567)
    at org.apache.spark.SparkContext.runJob(SparkContext.scala:1822)
    at org.apache.spark.SparkContext.runJob(SparkContext.scala:1835)
    at org.apache.spark.SparkContext.runJob(SparkContext.scala:1848)
    at org.apache.spark.SparkContext.runJob(SparkContext.scala:1919)
    at org.apache.spark.rdd.RDD$$anonfun$collect$1.apply(RDD.scala:905)
    at org.apache.spark.rdd.RDDOperationScope$.withScope(RDDOperationScope.scala:147)
    at org.apache.spark.rdd.RDDOperationScope$.withScope(RDDOperationScope.scala:108)
    at org.apache.spark.rdd.RDD.withScope(RDD.scala:306)
    at org.apache.spark.rdd.RDD.collect(RDD.scala:904)
    at org.template.URModel.save(URModel.scala:122)
    at org.template.URModel.save(URModel.scala:38)
    at io.prediction.controller.P2LAlgorithm.makePersistentModel(P2LAlgorithm.scala:111)
    at io.prediction.controller.Engine$$anonfun$makeSerializableModels$2.apply(Engine.scala:294)
    at io.prediction.controller.Engine$$anonfun$makeSerializableModels$2.apply(Engine.scala:293)
    at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
    at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
    at scala.collection.Iterator$class.foreach(Iterator.scala:727)
    at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
    at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
    at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
    at scala.collection.TraversableLike$class.map(TraversableLike.scala:244)
    at scala.collection.AbstractTraversable.map(Traversable.scala:105)
    at io.prediction.controller.Engine.makeSerializableModels(Engine.scala:293)
    at io.prediction.controller.Engine.train(Engine.scala:185)
    at io.prediction.workflow.CoreWorkflow$.runTrain(CoreWorkflow.scala:65)
    at io.prediction.workflow.CreateWorkflow$.main(CreateWorkflow.scala:247)
    at io.prediction.workflow.CreateWorkflow.main(CreateWorkflow.scala)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.apache.spark.deploy.SparkSubmit$.org$apache$spark$deploy$SparkSubmit$$runMain(SparkSubmit.scala:672)
    at org.apache.spark.deploy.SparkSubmit$.doRunMain$1(SparkSubmit.scala:180)
    at org.apache.spark.deploy.SparkSubmit$.submit(SparkSubmit.scala:205)
    at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:120)
    at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)
</code></pre>