400-Bad Request - The request could not be understood by the server due to incorrect syntax.
401 -Unauthorized User - authentication is required.
403 - Forbidden - The server understood the request, but is refusing to fulfill it.
404 - Page Not Found - The server has not found anything matching the Request-URI.
405 - Method Not Allowed - The method specified in the Request-Line is not allowed for the resource identified by the Request-URI.
406 - Not Acceptable - The server cannot generate a response that the requestor is willing to accept.
407 - Proxy Authentication Required - This code is similar to 401 (Unauthorized), but indicates that the client must first authenticate itself with the proxy.
408 - Request Timed Out - The server stopped waiting for a client request.
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 at the server and no forwarding address is known. This condition is similar to 404, except that the 410 error condition is expected to be permanent.
411 - Length Required - The server requires a content-length in the request.
412 - Precondition Failed - The precondition given in one or more of the request-header fields evaluated to false when it was tested on the server.
413 - Request Entity Too Large - The server is refusing to process a request because the request entity is larger than the server is willing or able to process.
414 - Request URL Too Long - The server is refusing to service the request because the Request-URI is longer than the server is willing to interpret.
415 - Unsupported Media Type - The server is refusing to service the request because the entity of the request is in a format not supported by the requested resource for the requested method.
500 - Server Error - Internal Web server error
501 - No Server - Function not implemented in Web server software
502 - Server Overload - Bad Gateway; a server being used by this Web server has sent an invalid response.
503 - Service Unavailable - Service unavailable because of temporary overload or maintenance.
504 - Gateway Timeout - A server being used by this server has not responded in time.
505 - HTTP Version Not Supported - The server does not support the HTTP protocol version that was used in the request message.
