Error Codes — See appropriate web server error codes below.

• 0 Error (Server Error) — No connection to the server available or the server was unavailable.
• 300 Error (Multiple Choices) — The requested resource corresponds to multiple representations, each with its own specific location, and the negotiation information is being provided so that the user can select a preference and redirect its request to that location.
• 301 Error (Moved Permanently) — The requested resource has been assigned to a new permanent URL.
• 302 Error (Moved Temporarily) — The requested resource resides temporarily under a different URL. Clients should continue to use the URL since the redirection may vary.
• 303 Error (See Other) — The response to the request can be found under a different URL. The new URL is not a substitute reference for the originally requested resource.
• 304 Error (Not Modified) — If the client has performed a conditional GET request and access is allowed, but the document has not been modified.
• 305 Error (Use Proxy) — The requested resource must be accessed through the proxy given by the location field.
• 400 Error (Bad Request) — The request is not understood by the server due to an incorrect syntax.
• 401 Error (Unauthorized) — User authentication is required.
• 403 Error (Forbidden) — The server understood the request, but is refusing to fulfill it.
• 404 Error (Page Not Found) — The server has not found the URL requested.
• 405 Error (Method Not Allowed) — The method specified in the Request-Line is not allowed for the resource identified by the Request-URL.
• 406 Error (Not Acceptable) — The server is not sending a response that the requestor is willing to accept.
• 407 Error (Proxy Authentication Required) — The client must authenticate itself with the proxy (similar to Unauthorized).
• 408 Error (Request Timed Out) — The client did not produce a request within the time that the server was prepared to wait.
• 409 Error (Conflict) — The request was not complete due to a conflict with the current state of resources.
• 410 Error (Gone) — The requested resource is no longer available at the server and no forwarding address is known (similar to 404, but 410 is permanent).
• 411 Error (Length Required) — The server refuses to accept the request without a defined content-length.
• 412 Error (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 Error (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 Error (Request-URL Too Long) — The request entity is larger than the server is willing or able to interpret.
• 415 Error (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.
• 416 Error (Requested Range Not Satisfiable) — The request included a Range request-header field, and not any of the range-specifier values in this field overlap the current extent of the selected resource, and also the request did not include an If-Range request-header field.
• 417 Error (Expectation Failed) — The expectation given in the Expect request-header could not be fulfilled by the server.
• 500 Error (Server Error) — The client’s Web server is incapable of performing the request.
• 501 Error (Not Implemented) — The server is currently unable to handle the request due to a temporary overloading or maintenance of the server.
• 502 Error (Bad Gateway) — The server received an invalid response from the upstream server that it accessed in attempting to fulfill the request.
• 503 Error (Out of Resources) — The server is unable to handle the request due to a temporary overloading or maintenance of the server.
• 504 Error (Gateway Timeout) — The server did not receive a response in time from the upstream server specified by the URL.
• 505 Error (HTTP Version Not Supported) — The server does not support the HTTP protocol version that was used in the request message.