Symptom:
ModPerson transaction failed if security profile changed to None from LDAP profile.

Conditions:
1) Have a Location associated to LDAP authentication server
2) The end users in this Location will have the "LDAP" security profile.
3) Now navigate to Location Administration > End Users and select an end user.
4) Change the Security Profile from "LDAP" to "None" in the drop-down menu and Modify.
5) The transaction will fail with the following error:

466553 Request Failed   ModPerson
    =>  Entered at: 2014/08/22 14:13:03 EDT  (10.10.12.122)

        Password change operation failed. Please contact your system administrator.
    => Started at: 2014/08/22 14:13:03 EDT
            => End at: 2014/08/22 14:13:05 EDT