The website sometimes allows the filer to click the Edit (pencil) or Delete (trash can) icons to the right of Service Contacts regardless of who added the Service Contact entry.
However, only the Individual or Firm Account that added a Service Contact can edit or delete a Service Contact entry. If you or someone in your Firm account did not add a given email address to a case's Service Contacts list, then you cannot edit or remove it. This includes trying to change the Associated Party.
If a filer who did not add a given Service Contact entry attempts to edit it - by trying to edit the email address or the Associated Party, for example - then the red "Unknown error occurred" message will appear. (See below.)
If the filer does not want a given Service Contact that they did not add to receive eservice, then the filer should uncheck that contact instead of trying to edit/delete them. You cannot edit or remove a Service Contact you did not add to the case.
NOTE: This error can also appear if a filer tries to add a Service Contact from the Party List. To resolve the error, add the Service Contact as a new contact instead.