On the Ambari Server, obtain the JCE policy file appropriate for the JDK version in your cluster.

For example:

wget --no-check-certificate --no-cookies --header "Cookie: oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jce/8/jce_policy-8.zip"

Save the policy file archive in a temporary location.

On Ambari Server and on each host in the cluster, add the unlimited security policy JCE jars to $JAVA_HOME/jre/lib/security/.

For example, run the following to extract the policy jars into the JDK installed on your host:

unzip -o -j -q jce_policy-8.zip -d /usr/jdk64/jdk1.8.0_40/jre/lib/security/

Restart Ambari Server: sudo ambari-server restart

Proceed to Running the Security Wizard.