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# Problem types

Every non-2xx response is an [RFC 9457](https://www.rfc-editor.org/rfc/rfc9457)
`application/problem+json` document whose `type` links to one of the pages below. Branch on the
machine-readable `code` (not the human-readable `title`). See [Errors](/guides/core-concepts/errors) for the full body
shape and handling patterns.

| Status | Type                                                             | Title                                                         |
| ------ | ---------------------------------------------------------------- | ------------------------------------------------------------- |
| `400`  | [`bad_request`](/api/problems/bad_request)                       | The request was malformed.                                    |
| `401`  | [`unauthorized`](/api/problems/unauthorized)                     | Authentication is required or the API key is invalid.         |
| `403`  | [`forbidden`](/api/problems/forbidden)                           | You are not permitted to perform this action.                 |
| `404`  | [`not_found`](/api/problems/not_found)                           | The requested resource was not found.                         |
| `405`  | [`method_not_allowed`](/api/problems/method_not_allowed)         | The HTTP method is not allowed here.                          |
| `409`  | [`conflict`](/api/problems/conflict)                             | The request conflicts with the current state of the resource. |
| `415`  | [`unsupported_media_type`](/api/problems/unsupported_media_type) | The request media type is not supported.                      |
| `422`  | [`validation_error`](/api/problems/validation_error)             | Your request parameters did not validate.                     |
| `429`  | [`rate_limited`](/api/problems/rate_limited)                     | Rate limit exceeded.                                          |
| `500`  | [`internal_error`](/api/problems/internal_error)                 | An unexpected error occurred.                                 |
| `502`  | [`bad_gateway`](/api/problems/bad_gateway)                       | An upstream service returned an invalid response.             |
| `503`  | [`service_unavailable`](/api/problems/service_unavailable)       | The service is temporarily unavailable.                       |
| `504`  | [`gateway_timeout`](/api/problems/gateway_timeout)               | An upstream service timed out.                                |