With the help of a very experienced hadoop user, I got my sandbox running in VirtualBox with the following steps: (1) In Ambari, saw that NameNode was not starting up correctly: * Click on "ops" link to the right of "Sandbox" on top of page * Click on "Start HDFS" link in "Background Operations Running list * Click on "sandbox-hdp.hortonworks.com" link * Click on "NameNode Start" link to see log: 2018-03-13 21:49:05,396 - Waiting up to 19 minutes for the NameNode to leave Safemode... 2018-03-13 21:49:05,397 - Execute['/usr/hdp/current/hadoop-hdfs-namenode/bin/hdfs dfsadmin -fs hdfs://sandbox-hdp.hortonworks.com:8020 -safemode get | grep 'Safe mode is OFF''] {'logoutput': True, 'tries': 115, 'user': 'hdfs', 'try_sleep': 10} 2018-03-13 21:49:10,605 - Retrying after 10 seconds. Reason: Execution of '/usr/hdp/current/hadoop-hdfs-namenode/bin/hdfs dfsadmin -fs hdfs://sandbox-hdp.hortonworks.com:8020 -safemode get | grep 'Safe mode is OFF'' returned 1. (2) Using putty, ssh to 127.0.0.1 port 2222 log in as root and run: [root@sandbox-hdp ~]# sudo -u hdfs hadoop dfsadmin -safemode leave Safe mode is OFF (3) In Ambari Dashboard on bottom left, in Actions menu, restart all services by: * Click "Stop All" link and wait until completed * Click "Start All" link and wait until completed ... View more