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unknown_enum_value

422 Unprocessable Content   The value is not one this field accepts.

When you get it

The value is not one this field accepts. It is always answered with HTTP 422 - one code means one status, so a client may key its handling on either.

Fields it carries

Inside each errors[] entry, beside pointer:

pointer

RFC 6901 JSON Pointer to the offending value in the request body.

parameter

The query parameter the failure is about - the query-side twin of `pointer`.

value

The value the request sent, echoed back so the caller can see what was read.

allowed

The complete set of values this field accepts. Send one of these.

reason

The machine-readable sub-case, when one code covers several. Branch on it.

didYouMean

The registered name closest to the one you sent - usually the fix is this spelling.

expected

What this member should have been. On `wrong_type` it is the JSON type the member must have - `string`, `number`, `integer`, `boolean`, `object`, `array` or `null` - and an array of those names when more than one is accepted (`["string", "null"]` means the member is nullable). On a selection mismatch it is instead the count YOUR preview reported while `actual` is what the server counts NOW - the drift is the point. Where the refusal is about a token or a flag, it is the value the server required.

A field is omitted when the server genuinely does not know it - an absent member is never the same as an empty one.

How to fix it

The request was well-formed but a value is not acceptable. The fields above name the offending value and what would be accepted - fix the request and retry.

Shape

{
  "type":   "https://api2.host-tracker.com/problems/unknown-enum-value",
  "title":  "The value is not one this field accepts.",
  "status": 422,
  "code":   "unknown_enum_value",
  "errors": [
    { "pointer": …, "parameter": …, "value": …, "allowed": …, "reason": …, "didYouMean": …, "expected": … }
  ]
}