Hello, Restarting the Standby NameNode did not resolve the issue. Then when trying to restart the Active NameNode Ambari told me to SSH into my Active NameNode server and: Enter Safe Mode sudo su hdfs -l -c 'hdfs dfsadmin -safemode enter' Safe mode is ON in xx.xxx.xxx.xxx:8020 Safe mode is ON in xx.xxx.xxx.xxx:8020 The save Namespace root@xxxxx:~# sudo su hdfs -l -c 'hdfs dfsadmin -saveNamespace' Save namespace successful for xx.xxx.xxx.xxx:8020 Save namespace successful for xx.xxx.xxx.xxx:8020 After that restarting both NameNodes cleared the Alerts. Regards. ... View more