| Unprocessable Entity
| The request was well-formed but was unable to be followed due to semantic errors. For example, a client sends a invalid field value (numbers instead of characters) in a JSON object.
|-
| 428
| Precondition Required
| The client did not provide a proper ETag and/or Last-modification header when updating an object via PUT, see http://tools.ietf.org/html/rfc6585#section-3
|-
| 429
| Too Many Requests
| There were too many requests within a given time-period, see http://tools.ietf.org/html/rfc6585#section-4
|-