a however would make sense is  resource  did not exist there are cases like  you know neutron  when you get a because a resource does not exist  whereas the truth is that the resource does not exist on that specific instance of the server  because the extensions that implements it is not defined  this was a place were some   idiot   me  proposed initially we should instead use the i justified myself saying i was talking about jeans from a famous brand  i think is the only one that makes some sense  however  as a side note  i think you too are aware that we are using for quite a lot of stuff  and the only way of distinguishing the various errors is the message  messages are good for humans  not so for machines  are we still completely on the idea of sending application error codes within error response bodies 