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filter_required

422 Unprocessable Content   This operation refuses to run without an explicit filter.

When you get it

This operation refuses to run without an explicit filter. 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:

parameter

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

operation

The operation the refusal is about.

hint

A concrete next step for this refusal.

reason

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

preview

The endpoint that will preview this selection and hand back the token the operation needs.

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.

value

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

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/filter-required",
  "title":  "This operation refuses to run without an explicit filter.",
  "status": 422,
  "code":   "filter_required",
  "errors": [
    { "parameter": …, "operation": …, "hint": …, "reason": …, "preview": …, "expected": …, "value": … }
  ]
}