A rejected error can occur if extreme market conditions lead to a quote being invalidated. In this case, a new quote most be issued to the user. 
{
  "detail": "extreme market conditions have invalidated this quote execution",
  "meta": {},
  "status": 403,
  "title": "Rejected",
  "type": "https://developer.paxos.com/docs/v2/problems/rejected"
}