1 Could not find or load main class org.apache.hadoop.mapreduce.v2.app.MRAppMaster

（1）找到$HADOOP_HOME/etc/mapred-site.xml,增加以下配置

<property><name>yarn.app.mapreduce.am.env</name><value>HADOOP_MAPRED_HOME=${HADOOP_HOME}</value>
</property>
<property><name>mapreduce.map.env</name><value>HADOOP_MAPRED_HOME=${HADOOP_HOME}</value>
</property>
<property><name>mapreduce.reduce.env</name><value>HADOOP_MAPRED_HOME=${HADOOP_HOME}</value>
</property>

（2）将配置文件分发到各个节点

（3）重新启动YARN集群

2 Caused by: java.net.ConnectException: Call to node2.itcast.cn/192.168.88.101:16020 failed on connection exception: org.apache.hbase.thirdparty.io.netty.channel.ConnectTimeoutException: connection timed out: node2.itcast.cn/192.168.88.101:16020

无法连接到HBa