# API Error Codes

The Retreaver Core API uses the following error codes:

| Error Code | Meaning                                                                             |
| ---------- | ----------------------------------------------------------------------------------- |
| 400        | Bad Request -- Your request was unintelligible. Check your formatting.              |
| 401        | Unauthorized -- Your API key is wrong or missing.                                   |
| 403        | Forbidden -- You're authenticated, but you don't have permission to access this resource. |
| 404        | Not Found -- It actually, really doesn't exist.                                     |
| 405        | Method Not Allowed -- It doesn't respond to the HTTP action you used.               |
| 406        | Not Acceptable -- You requested a format that isn't JSON, or, sigh, XML.            |
| 410        | Gone -- It up and left or was otherwise deleted.                                    |
| 418        | I'm a little teapot!                                                                |
| 429        | Too Many Requests -- Returned by certain rate-limited endpoints. Slow down. Highly concurrent requests are frowned upon. |
| 500        | Internal Server Error -- We had a problem with our server. Try again later.         |
| 503        | Service Unavailable -- We're temporarily offline for maintenance. Please try again later. |

JSON error responses generally use either an `error` string or an `errors` collection/hash, depending on the endpoint. Refer to each endpoint's response documentation for the exact shape.