All status code that begins with the number 4 are error code.
Meaning that an error has occurred during the request and that the server may use any of this code to send feedback about bad request parameters for instance.
The specification calls this type of error error caused by the client and makes a distinction with the error of the server that is classified with a 5XX number.
| Code | Description |
|---|---|
| 400 | Bad Request |
| 401 | Unauthorized |
| 402 | Payment Required |
| 403 | Forbidden |
| 404 | Not Found |
| 405 | Method Not Allowed |
| 406 | Not Acceptable (send for instance when the requested media type cannot be send) |
| 407 | Proxy Authentication Required |
| 408 | Request Timeout |
| 409 | Conflict |
| 410 | Gone |
| 411 | Length Required |
| 412 | Precondition Failed |
| 413 | Request Entity Too Large |
| 414 | Request-URI Too Long |
| 415 | Unsupported Media Type |
| 416 | Requested Range Not Satisfiable |
| 417 | Expectation Failed |
| 422 | Unprocessable Entity (The client should not repeat this request without modification.) |
| 444 | A non-standard status code used to instruct nginx to close the connection without sending a response to the client, most commonly used to deny malicious or malformed requests. - This status code is not seen by the client, it only appears in nginx log files. (you may also send a 503 (Service Temporarily Unavailable)) |