Suppose I have the following resource collection
/api/people
With each resource identified by their IDs
/api/people/1
/api/people/2
...and so on...
Updating is done by sending POST request carrying payload the data to be updated
POST /api/people/20
{"name":"Yan"}
If such update is failing because there's no resource under that ID (in example above is 20) which HTTP status code should be returned.
404 Not Found? Justification being the resource under that URI does not exists.
400 Client Error? Justification being client has failed constructing proper request.
Other statuses?