Show server side validation errors after form submission failed

How can I show validation messages after a form submission fails? The API request returns an HTTP 400 response "application / problem + json" and contains violations in the form of a list with a field.

https://tools.ietf.org/html/rfc7807#section-3

{
   "type": "https://example.net/validation-error",
   "title": "Your request parameters didn't validate.",
   "invalid-params": [ 
      {
         "name": "age",
         "reason": "must be a positive integer"
      },
      {
         "name": "color",
         "reason": "must be 'green', 'red' or 'blue'"
      }
   ]
}