Two properties (that is, yarn.nodemanager.aux-services and yarn.nodemanager.aux-services.mapreduce.shuffle.class) need to be set to the etc/hadoop/yarn-site.xml file. Just copy the following lines of codes:

<configuration>
<property>
   <name>yarn.nodemanager.aux-services</name>
   <value>mapreduce_shuffle</value>
 </property>
 <property>
   <name>yarn.nodemanager.aux-services.mapreduce.shuffle.class</name>
   <value>org.apache.hadoop.mapred.ShuffleHandler</value>
 </property>
</configuration>