Upgrade each JournalNode process one by one. The order does not matter.
Stop, switch, and start each JournalNode:
su - hdfs -c
"/usr/hdp/current/hadoop-hdfs-journalnode/../hadoop/sbin/hadoop-daemon.sh stop
journalnode"
hdp-select set hadoop-hdfs-journalnode 2.2.6.0-2800
su - hdfs -c
"/usr/hdp/current/hadoop-hdfs-journalnode/../hadoop/sbin/hadoop-daemon.sh start
journalnode"
