Hi,
There have been a fix in SEP 12.1 RU4 version.
Check whether you have been affected by the same.
Management Server Configuration Wizard encounters Unexpected Server Error
Fix ID: 3064213
Symptom: An Unexpected Server Error occurs after you run the Management Server Configuration Wizard.
Solution: Corrected the method that compared and stored server names in the database.
Reference: New fixes and features in Symantec Endpoint Protection 12.1.4