启动hdfs后执行share目录中自带的mapreduce程序时报如下错误
找到$HADOOP_HOME/etc/mapred-site.xml,增加以下配置
1 <property>
2 <name>yarn.app.mapreduce.am.env</name>
3 <value>HADOOP_MAPRED_HOME=${HADOOP_HOME}</value>
4 </property>
5 <property>
6 <name>mapreduce.map.env</name>
7 <value>HADOOP_MAPRED_HOME=${HADOOP_HOME}</value>
8 </property>
9 <property>
10 <name>mapreduce.reduce.env</name>
11 <value>HADOOP_MAPRED_HOME=${HADOOP_HOME}</value>
12 </property>
hadoop 3.1.1 Could not find or load main class org.apache.hadoop.mapreduce.v2.app.MRAppMaster
原文：https://www.cnblogs.com/tele-share/p/9497613.html