Reply To: pgrade HDP-2.2.4.2-2 to HDP-2.3.0.0 using Ambari

Igor,

I had the same reaction than you at the beginning

You actually need to select HDFS the  on the left side click on service actions and choose Enable NameNode HA before making any automatic upgrade through ambari.

This operation will himself take the lead in order to delete the secondary namenode.

This documentation was usefull for me before activate the HA namenode

http://docs.hortonworks.com/HDPDocuments/Ambari-2.1.1.0/bk_Ambari_Users_Guide/content/_how_to_configure_namenode_high_availability.html

Have fun.