The short answer is, I’d get errors like the following when I try to run a MapReduce job:
Log Type: stderr
Log Upload Time: Thu Oct 27 00:16:23 +0000 2016
Log Length: 88
Error: Could not find or load main class org.apache.hadoop.mapreduce.v2.app.MRAppMaster
This was a rather vexing issue for a long time for me.