We're running a job that's issuing NullPointerException without traces of our job's code.

Does anybody know what would be the best course of action when it comes to debugging these issues?

The job is a Scala job running on DBR 11.3 LTS.

In case it's related with the issue, the job targets both AWS S3 and AWS Redshift for I/O.

Here's one of the stack traces

Job aborted due to stage failure: Task 267 in stage 30.0 failed 4 times, most recent failure: Lost task 267.3 in stage 30.0 (TID 6343) (10.218.226.53 executor 2): java.lang.NullPointerException
	at org.apache.spark.unsafe.map.BytesToBytesMap.safeLookup(BytesToBytesMap.java:534)
	at org.apache.spark.sql.execution.joins.UnsafeHashedRelation.get(HashedRelation.scala:231)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage2.hashAgg_doAggregateWithKeys_0$(Unknown Source)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage2.processNext(Unknown Source)
	at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43)
	at org.apache.spark.sql.execution.WholeStageCodegenExec$$anon$1.hasNext(WholeStageCodegenExec.scala:761)
	at scala.collection.Iterator$$anon$10.hasNext(Iterator.scala:460)
	at org.apache.spark.shuffle.sort.UnsafeShuffleWriter.write(UnsafeShuffleWriter.java:195)
	at org.apache.spark.shuffle.ShuffleWriteProcessor.write(ShuffleWriteProcessor.scala:59)
	at org.apache.spark.scheduler.ShuffleMapTask.$anonfun$runTask$3(ShuffleMapTask.scala:81)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.ShuffleMapTask.$anonfun$runTask$1(ShuffleMapTask.scala:81)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:53)
	at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:41)
	at org.apache.spark.scheduler.Task.doRunTask(Task.scala:169)
	at org.apache.spark.scheduler.Task.$anonfun$run$4(Task.scala:137)
	at com.databricks.unity.EmptyHandle$.runWithAndClose(UCSHandle.scala:104)
	at org.apache.spark.scheduler.Task.$anonfun$run$1(Task.scala:137)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.Task.run(Task.scala:96)
	at org.apache.spark.executor.Executor$TaskRunner.$anonfun$run$13(Executor.scala:902)
	at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1696)
	at org.apache.spark.executor.Executor$TaskRunner.$anonfun$run$4(Executor.scala:905)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:760)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:750)
 
Driver stacktrace:
Caused by: NullPointerException: 
at org.apache.spark.unsafe.map.BytesToBytesMap.safeLookup(BytesToBytesMap.java:534)
	at org.apache.spark.sql.execution.joins.UnsafeHashedRelation.get(HashedRelation.scala:231)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage2.hashAgg_doAggregateWithKeys_0$(Unknown Source)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage2.processNext(Unknown Source)
	at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43)
	at org.apache.spark.sql.execution.WholeStageCodegenExec$$anon$1.hasNext(WholeStageCodegenExec.scala:761)
	at scala.collection.Iterator$$anon$10.hasNext(Iterator.scala:460)
	at org.apache.spark.shuffle.sort.UnsafeShuffleWriter.write(UnsafeShuffleWriter.java:195)
	at org.apache.spark.shuffle.ShuffleWriteProcessor.write(ShuffleWriteProcessor.scala:59)
	at org.apache.spark.scheduler.ShuffleMapTask.$anonfun$runTask$3(ShuffleMapTask.scala:81)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.ShuffleMapTask.$anonfun$runTask$1(ShuffleMapTask.scala:81)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:53)
	at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:41)
	at org.apache.spark.scheduler.Task.doRunTask(Task.scala:169)
	at org.apache.spark.scheduler.Task.$anonfun$run$4(Task.scala:137)
	at com.databricks.unity.EmptyHandle$.runWithAndClose(UCSHandle.scala:104)
	at org.apache.spark.scheduler.Task.$anonfun$run$1(Task.scala:137)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.Task.run(Task.scala:96)
	at org.apache.spark.executor.Executor$TaskRunner.$anonfun$run$13(Executor.scala:902)
	at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1696)
	at org.apache.spark.executor.Executor$TaskRunner.$anonfun$run$4(Executor.scala:905)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:760)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:750)
 
Driver stacktrace:
	at org.apache.spark.scheduler.DAGScheduler.failJobAndIndependentStages(DAGScheduler.scala:3312)
	at org.apache.spark.scheduler.DAGScheduler.$anonfun$abortStage$2(DAGScheduler.scala:3244)
	at org.apache.spark.scheduler.DAGScheduler.$anonfun$abortStage$2$adapted(DAGScheduler.scala:3235)
	at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:62)
	at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:55)
	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:49)
	at org.apache.spark.scheduler.DAGScheduler.abortStage(DAGScheduler.scala:3235)
	at org.apache.spark.scheduler.DAGScheduler.$anonfun$handleTaskSetFailed$1(DAGScheduler.scala:1424)
	at org.apache.spark.scheduler.DAGScheduler.$anonfun$handleTaskSetFailed$1$adapted(DAGScheduler.scala:1424)
	at scala.Option.foreach(Option.scala:407)
	at org.apache.spark.scheduler.DAGScheduler.handleTaskSetFailed(DAGScheduler.scala:1424)
	at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.doOnReceive(DAGScheduler.scala:3524)
	at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:3462)
	at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:3450)
	at org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:51)
Caused by: java.lang.NullPointerException
	at org.apache.spark.unsafe.map.BytesToBytesMap.safeLookup(BytesToBytesMap.java:534)
	at org.apache.spark.sql.execution.joins.UnsafeHashedRelation.get(HashedRelation.scala:231)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage2.hashAgg_doAggregateWithKeys_0$(Unknown Source)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage2.processNext(Unknown Source)
	at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43)
	at org.apache.spark.sql.execution.WholeStageCodegenExec$$anon$1.hasNext(WholeStageCodegenExec.scala:761)
	at scala.collection.Iterator$$anon$10.hasNext(Iterator.scala:460)
	at org.apache.spark.shuffle.sort.UnsafeShuffleWriter.write(UnsafeShuffleWriter.java:195)
	at org.apache.spark.shuffle.ShuffleWriteProcessor.write(ShuffleWriteProcessor.scala:59)
	at org.apache.spark.scheduler.ShuffleMapTask.$anonfun$runTask$3(ShuffleMapTask.scala:81)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.ShuffleMapTask.$anonfun$runTask$1(ShuffleMapTask.scala:81)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:53)
	at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:41)
	at org.apache.spark.scheduler.Task.doRunTask(Task.scala:169)
	at org.apache.spark.scheduler.Task.$anonfun$run$4(Task.scala:137)
	at com.databricks.unity.EmptyHandle$.runWithAndClose(UCSHandle.scala:104)
	at org.apache.spark.scheduler.Task.$anonfun$run$1(Task.scala:137)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.Task.run(Task.scala:96)
	at org.apache.spark.executor.Executor$TaskRunner.$anonfun$run$13(Executor.scala:902)
	at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1696)
	at org.apache.spark.executor.Executor$TaskRunner.$anonfun$run$4(Executor.scala:905)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:760)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:750)