# unsupported_field: A field or include is not offered

Status 400.

## Why it happens

`fields` or `include` names a key this endpoint does not offer.

## What to do

Use the names in the `allowed` member of the answer, or the endpoint's response table.

## Example

```json
{
  "type": "https://unique.domains/api/problems/unsupported_field",
  "title": "A field or include is not offered",
  "status": 400,
  "detail": "Unknown field: nope.",
  "instance": "/v1/tlds",
  "code": "unsupported_field",
  "allowed": [
    "tld",
    "slug",
    "ianaStatus",
    "kind",
    "ianaType",
    "registryOperator",
    "registryCountryCode",
    "isBrand",
    "isIdn",
    "delegatedOn",
    "removedOn",
    "contractTerminated",
    "rdapServer",
    "category",
    "phases",
    "insights"
  ]
}
```

All errors: https://unique.domains/api/problems