If you are using Cisco ISE posture module at your work place or for your remote clients then you probably came across where the client searches for the policy server and comes back with the message that no policy server is found. this could be due many reasons.
One of the reason is that it is due to bug listed in the link below and error message in the picture below
https://quickview.cloudapps.cisco.com/quickview/bug/CSCvd06182
I have also seen that where yours AAA servers sometimes stops responding for whatever reason or your ASA fails over the AAA server to the backup one and the back up server may not be configured correctly. This is the case in many firms where the DR server is configured but never tested to confirm that the fail over configurations works
before you think it is due to the Cisco bug, make sure that your AAA server is active and responding and you can do this by going to the ASA using ssh or console and running the following command
running the “sh aaa servers” will show you the active servers – make sure that your primary ISE server is responding
Once the device is complaint – below is what you should see