End the normal (or deisrable) end of a process by the none event and the business exception (or unwanted end) by the error event. Use the attached event at the above level of the model.
✔ How to
✘ How NOT to
Notes
Technically, attached event can be omitted - in this case error event would stop the current subprocess, the subprocesses above and the top-level process. Yet if modelled this way, the significant aspects of the process behavior would be hidden so the good practice is to always depict the attached error event.
If the attached event is named then it'd catch only the end error event with the same name. This way each end event can be processed separately. If the attached event is unnamed it'd catch all end error events.