The ProxySG returns the error message
"Could not set user-defined exception field: Could not find exception with the given name"
when trying to create a user defined exception
Registry corruption can result in this error message
Once the registry corruption has been confirmed the only solution is to run a restore factory defaults on the affected ProxySG
To minimize the possibility of corruption please make sure to upgrade to the latest version of SGOS, upgrading will NOT resolve the issue