表27.2状态码（续） Code Phrase Description Redirection 301 Moved permanently The requested URL is no longer used by the server. 302 Moved temporarily The requested URL has moved temporarily. 304 Not modified The document has not been modified. Client Error 400 Bad request There is a syntax error in the request. 401 Unauthorized The request lacks proper authorization. 403 Forbidden Service is denied. 404 Not found The document is not found. 405 Method not allowed The method is not supported in this URL. 406 Not acceptable The format requested is not acceptable. Server Error 500 Internal server error There is an error,such as a crash,at the server site. 501 Not implemented The action requested cannot be performed. 503 Service unavailable The service is temporarily unavailable,but may be requested in the future. 27.25 27.25 表 27.2 状态码(续)