Core issue
In this issue, if you make any configuration changes on the ACS SE in Network Configuration, this locks the ACS SE.
For example, if you add an AAA client, as soon as administrator presses Submit, ACS SE locks. The only way to get back is to reboot the ACS SE or restart the CSAdmin from console.
This issue usually occurs if Remote Agent entry is at a version earlier or later than the version that ACS SE currently runs.
Resolution
In order to resolve this issue, choose Network Configuration > Remote Agent and remove any Remote Agent entry that is at a version earlier or later than the version of ACS SE.
For example, if ACS SE is at version 4.1, remove any values other than 4.1 for remote agent.
Refer to the Configuring Remote Agents (ACS Solution Engine Only) section of Network Configuration for more information.