`validation_failed`

422 Unprocessable Content The request body or query is not valid.

When you get it

The request body or query is not valid. 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`.
detail: Human-readable detail for this one occurrence. Never the only place remediation appears.
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.
min: The smallest value this field accepts, inclusive.
max: The largest value this field accepts, inclusive.
didYouMean: The registered name closest to the one you sent - usually the fix is this spelling.
expiresIn: How long the value is valid for, in seconds, counted from when it was issued.
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.
minItems: The fewest items this operation accepts in one request. An empty or absent list is refused rather than treated as "none".
maxItems: The most items this operation accepts in one request - the same fact as `limit`, under the spelling this endpoint uses.
alternatives: Other ways to express the same request that this operation does accept. Send one of these shapes instead.
oneOf: Members of which exactly one satisfies the requirement - send any single one of them, not all.
existingId: The id of the resource that already holds the key you tried to claim.
retryAfterSeconds: How long to wait before retrying, in seconds. Mirrors the Retry-After header.

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/validation-failed",
  "title":  "The request body or query is not valid.",
  "status": 422,
  "code":   "validation_failed",
  "errors": [
    { "pointer": …, "parameter": …, "detail": …, "value": …, "allowed": …, "reason": …, "min": …, "max": …, "didYouMean": …, "expiresIn": …, "expected": …, "minItems": …, "maxItems": …, "alternatives": …, "oneOf": …, "existingId": …, "retryAfterSeconds": … }
  ]
}