If your cluster is configured for Kerberos, double-check WebHDFS Authorization setting and confirm the “proxyuser=” part of the string is set to the Ambari Server principal name.

For example:

auth=KERBEROS;proxyuser=ambari-server

Refer to Kerberos Settings.

500 User: ambari-server is not allowed to impersonate admin

HDFS has not been configured for Ambari as a proxy user.

Refer to Configuring Your Cluster.

500 SIMPLE authentication is not enabled. Available:[TOKEN, KERBEROS]

If your cluster is configured for Kerberos, you cannot use the Local Cluster Configuration option. You must use the Custom Cluster Configuration option and enter the WebHDFS FileSystem URI.

For example:

webhdfs://namenode:50070

Refer to Cluster Configuration: Custom