Can you check all the hadoop environment variables are set properly in which the app master is getting launching.
If you are submitting from windows, this might be the issue https://issues.apache.org/jira/browse/MAPREDUCE-4052. Thanks Devaraj ________________________________ From: Subroto [ssan...@datameer.com] Sent: Tuesday, June 05, 2012 2:14 PM To: mapreduce-user@hadoop.apache.org Subject: java.lang.NoClassDefFoundError: org/apache/hadoop/mapreduce/v2/app/MRAppMaste Hi, While running MR Jobs over a yarn cluster I keep on getting: Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/hadoop/mapreduce/v2/app/MRAppMaster Caused by: java.lang.ClassNotFoundException: org.apache.hadoop.mapreduce.v2.app.MRAppMaster at java.net.URLClassLoader$1.run(URLClassLoader.java:202) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:248) Could not find the main class: org.apache.hadoop.mapreduce.v2.app.MRAppMaster. Program will exit. My client is running from a different environment from where the cluster is running. If I submit a job from the cluster environment; it runs successfully. I have verified the property yarn.application.classpath before submitting it from the client. The value is set to: $HADOOP_CONF_DIR,$HADOOP_COMMON_HOME/*,$HADOOP_COMMON_HOME/lib/*,$HADOOP_HDFS_HOME/*,$HADOOP_HDFS_HOME/lib/*,$HADOOP_MAPRED_HOME/*,$HADOOP_MAPRED_HOME/lib/*,$YARN_HOME/*,$YARN_HOME/lib/* Please let me know if I am missing anything. Cheers, Subroto Sanyal
