apachezeppelin:java.lang.NullPointerException

在zeppelin中运行任何类型的命令时,我得到一个"java.lang.NullPointerException"错误 - 甚至是简单的东西sc.appName.这是全文:

java.lang.NullPointerException
    at org.apache.zeppelin.spark.Utils.invokeMethod(Utils.java:38)
    at org.apache.zeppelin.spark.Utils.invokeMethod(Utils.java:33)
    at org.apache.zeppelin.spark.SparkInterpreter.createSparkContext_2(SparkInterpreter.java:391)
    at org.apache.zeppelin.spark.SparkInterpreter.createSparkContext(SparkInterpreter.java:380)
    at org.apache.zeppelin.spark.SparkInterpreter.getSparkContext(SparkInterpreter.java:146)
    at org.apache.zeppelin.spark.SparkInterpreter.open(SparkInterpreter.java:828)
    at org.apache.zeppelin.interpreter.LazyOpenInterpreter.open(LazyOpenInterpreter.java:70)
    at org.apache.zeppelin.interpreter.remote.RemoteInterpreterServer$InterpretJob.jobRun(RemoteInterpreterServer.java:483)
    at org.apache.zeppelin.scheduler.Job.run(Job.java:175)
    at org.apache.zeppelin.scheduler.FIFOScheduler$1.run(FIFOScheduler.java:139)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:748)

该错误似乎与Spark有关,但我在zeppelin-env.sh中正确设置了位置:

export SPARK_HOME=/usr/local/spark

我修改过的唯一其他字段如下:

export HADOOP_CONF_DIR=/home/cloudera/hadoop/etc/hadoop
export PYSPARK_PYTHON=/usr/bin/python
export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64/jre/

我的hadoop安装没有"conf"文件夹,但是yarn-site文件位于指定的位置.我正在使用匿名登录,不确定这是否相关.我可以从命令行成功运行Spark shell.我确实试图四处寻找,因为这是一个常见的错误,但似乎没有什么能适应这种情况.如果需要,我还可以提供zeppelin-env.sh文件.在此先感谢您的帮助!