## Error Messages

The Web browser supports the following HTTP standard Error Messages. The 4xx Status Codes indicate a client error in which the request contains bad syntax or cannot be fulfilled. The 5xx Status Codes indicate a server error in which the server failed to fulfill an apparently valid request.

Table 9: HTTP Error Messages
Status Code | Failure Message | Meaning
--- | --- | ---
400 | Bad Request | The request could not be understood by the server due to incorrect syntax.
401 | Unauthorized | The request requires user authentication. This message triggers display of the HTTP Authentication screen.
402 | Payment Required |
403 | Forbidden | The server has indicated it will not respond to your query.
404 | Not Found | The server has not found anything matching the request.
405 | Method Not Allowed |
406 | Not Acceptable |
407 | Proxy Authentication Required | The request requires user authentication. This message triggers display of the HTTP Authentication screen.
408 | Request Time-out |
409 | Conflict | The request could not be completed due to a conflict with the current state of the resource.
410 | Gone | The requested resource is no longer available.
411 | Length Required | The server refuses to accept the request.
412 | Precondition Failed |
413 | Request Entity Too Large | The server refuses to accept the request because the request entity is too large.
414 | Request-URI Too Large | The request-URI is longer than the server can interpret.
415 | Unsupported Media Type | The server refuses to accept the request because it is in an unsupported format.
416 | Requested range not satisfiable |
417 | Expectation Failed |
500 | Internal Server Error | The server encountered an unexpected condition that prevented it from fulfilling the request.
501 | Not Implemented |
502 | Bad Gateway | The server, while acting as a gateway or proxy, received an invalid response from the upstream server it accessed attempting to fulfill the request.
503 | Service Unavailable | The server is currently unable to handle the request due to a temporary overload or maintenance.
504 | Gateway Time-out | The server, while acting as a gateway or proxy, did not receive a timely response from the upstream server specified.
505 | HTTP Version not supported | The server does not support, or refuses to support, the HTTP protocol version used in the request message.

NOTE: When the client server receives a Status Code 431, it safely assumes there was something wrong with its request and treats the response as if it had received a Status Code 400.