Look up a Rails HTTP Status Code

428 - Precondition Required

Rails HTTP Status code :precondition_required

When to use status code 428

he origin server requires the request to be conditional. Intended to prevent "the 'lost update' problem, where a client GETs a resource's state, modifies it, and PUTs it back to the server, when meanwhile a third party has modified the state on the server, leading to a conflict."