Appendix C

Status Codes and Reason Phrases

The following information is a subset of an Internet draft known as Hypertext Transfer Protocol-HTTP/1.0 and is available at

http://www.ics.uci.edu/pub/ietf/http/draft-ietf-http-v10-spec-01.html

The status code element is a three-digit integer result code of an attempt to understand and satisfy a request. The reason phrase is intended to give a short, textual description of the status code. The status code is intended for use by the supporting software and the reason phrase is intended for the human user. The client is not required to examine or display the reason phrase.

The first digit of the status code defines the class of response. The last two digits do not have any categorization role. There are five values for the first digit, as shown in Table C.1.

Table C.1. Status codes and meanings.

Numeric	English	Meaning
`1xx`	Informational	This is not used; it is reserved for future use.
`2xx`	Success	The action was received, understood, and accepted.
`3xx`	Redirection	Further action must be taken in order to complete the request.
`4xx`	Client Error	The request contains bad syntax or cannot be fulfilled.
`5xx`	Server Error	The server failed to fulfill an apparently valid request.

Table C.2 lists the individual values of the numeric status codes defined for HTTP/1.0.

Table C.2. Status codes for HTTP/1.0.

Code	Reason Field	Meaning
`201`	`Created`	The request has been fulfilled and resulted in a new resource being created. The newly created resource can be referenced by the URI(s) returned in the URI-header field of the response, with the most specific URI for the resource given by a `Location` header field.
`202`	`Accepted`	The request has been accepted for processing, but the processing has not been completed.
`203`	`Non-Authoritative`	The returned metainformation in the `Entity-Information` header is not the definitive set as available from the origin server, but is gathered from a local or a third-party copy.
`204`	`No Content`	The server has fulfilled the request, but there is no new information to send back.
`300`	`Multiple Choices`	The requested resource is available at one or more locations and a preferred location could not be determined via content negotiation.
`301`	`Moved Permanently`	The requested resource has been assigned a new, permanent URI; any future references to this resource should be done using one of the returned URIs.
`302`	`Moved Temporarily`	The requested resource resides temporarily under a different URI.
`303`	`See Other`	The requested resource resides under a different URI and should be accessed using a `Get` method on that resource.
`304`	`Not Modified`	If the client has performed a conditional `Get` request and access is allowed, but the document has not been modified since the date and time specified in the `If-Modified-Since` field, the server responds with this status code and does not send an `Entity-Body` header to the client.
`400`	`Bad Request`	The request could not be understood by the server because it has a malformed syntax.
`401`	`Unauthorized`	The request requires user authentication. The response must include a `WWW-Authenticate` header field containing a challenge applicable to the requested resource.
`402`	`Payment Required`	This code is not currently supported, but it is reserved for future use.
`403`	`Forbidden`	The server understood the request but is refusing to perform the request because of an unspecified reason.
`404`	`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`	`None Acceptable`	The server has found a resource matching the request URI, but not one that satisfies the conditions identified by the `Accept` and `Accept-Encoding` request headers.
`407`	`Proxy Authentication (Unauthorized) Required`	This code is reserved for future use. Itis similar to `401`, but it indicates that the client first must authenticate itself with the proxy. HTTP/1.0 does not provide a means for proxy authentication.
`408`	`Request Timeout`	The client did not produce a request within the time that the server was prepared to wait.
`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.
`411`	`Authorization Refused`	The request credentials provided by the client were rejected by the server or insufficient to grant authorization to access the resource.
`500`	`Internal Server Error`	The server encountered an unexpected condition that prevented it from fulfilling the request.
`501`	`Not Implemented`	The server does not support the functionality required to fulfill the request.
`502`	`Bad Gateway`	The server received an invalid response from the gateway or upstream server it accessed when attempting to fulfill the request.
`503`	`Service Unavailable`	The server currently is unable to handle the request due to a temporary overloading or maintenance of the server.
`504`	`Gateway Timeout`	The server did not receive a timely response from the gateway or upstream server it accessed when attempting to complete the request.