Los códigos de clase 4XX indican que has hecho algo mal. Concretamente, hay un error en el lado del cliente.
Error HTTP 400 Bad Request
Error HTTP 401 Unauthorized
Error HTTP 402 Payment Required
Error HTTP 403 Forbidden
Error HTTP 404 Not Found
Error HTTP 405 Method Not Allowed
Error HTTP 406 Not Acceptable
Error HTTP 407 Proxy Authentication Required
Error HTTP 408 Request Timeout
Error HTTP 409 Conflict
Error HTTP 410 Gone
Error HTTP 411 Length Required
Error HTTP 412 Precondition Failed
Error HTTP 413 Payload Too Large
Error HTTP 414 Request-URI Too Long
Error HTTP 415 Unsupported Media Type
Error HTTP 416 Requested Range Not Satisfiable
Error HTTP 417 Expectation Failed
Error HTTP 418 I’m a teapot
Error HTTP 419 Authentication Timeout
Error HTTP 420
Error HTTP 421 Misdirected Request
Error HTTP 422 Unprocessable Entity
Error HTTP 423 Locked
Error HTTP 424 Failed Dependency
Error HTTP 425 Too Early
Error HTTP 426 Upgrade Required
Error HTTP 428 Precondition Required
Error HTTP 429 Too Many Requests
Error HTTP 431 Request Header Fields Too Large
Error HTTP 444 Connection Closed Without Response
Error HTTP 449 Retry With
Error HTTP 451 Unavailable For Legal Reasons
Error HTTP 460
Error HTTP 463
Error HTTP 464