The context is about giving a user advice on how to overcome an issue. To an end user: Merely displaying "Error code 429" is terrible, of course. "Contact the

The context is about giving a user advice on how to overcome an issue. To an end user: Merely displaying "Error code 429" is terrible, of course. "Contact the help desk like this and let them know the error code is 429" is better. Norman doesn't seem to be against this if there is nothing the user can do to handle the error on their own. If error code 429 is something the user can fix (maybe they need to wait 3 minutes before trying again), then just letting them know that is best.