If you are trying to add a new Non-Payroll User to ESS and getting the error: '\Oops, an unexpected error occurred'. This usually occurs when the Administrator name has been changed. To check this, go to
ESS, Settings, Roles & Permissions.
Select Administrator.
If the name has been altered, click Edit (pencil in the heading).
Change the Name back to Administrator.
Click Save.
If the error persists after restoring the correct name, raise a case online.