org.apache.hadoop.security.AccessControlException: Permission denied: user=root

This is a permissions issue. You can configure it and then restart the hadoop cluster to solve it. The current simple solution is:

1. Add parameters to hdfs-site.xml:

cd  hadoop260/etc/hadoop/

<property>
    <name>dfs.permissions</name>
    <value>false</value>
</property>

2 Configure zeppelin 

 3.Authorization 

hdfs dfs -chmod -R 777 /tmp

Then restart the hadoop cluster. If the slave is configured:

stop-all.sh

start-all.sh