When a browser requests a service from a web server, an error might occur.

This is a list of HTTP status messages that might be returned:

1xx: Information

Message:	Description:

100 Continue	The server has received the request headers, and the client should proceed to send the request body
101 Switching Protocols	The requester has asked the server to switch protocols
103 Checkpoint	Used in the resumable requests proposal to resume aborted PUT or POST requests

2xx: Successful

Message:	Description:

200 OK	The request is OK (this is the standard response for successful HTTP requests)
201 Created	The request has been fulfilled, and a new resource is created
202 Accepted	The request has been accepted for processing, but the processing has not been completed
203 Non-Authoritative Information	The request has been successfully processed, but is returning information that may be from another source
204 No Content	The request has been successfully processed, but is not returning any content
205 Reset Content	The request has been successfully processed, but is not returning any content, and requires that the requester reset the document view
206 Partial Content	The server is delivering only part of the resource due to a range header sent by the client

3xx: Redirection

Message:	Description:

300 Multiple Choices	A link list. The user can select a link and go to that location. Maximum five addresses
301 Moved Permanently	The requested page has moved to a new URL
302 Found	The requested page has moved temporarily to a new URL
303 See Other	The requested page can be found under a different URL
304 Not Modified	Indicates the requested page has not been modified since last requested
306 Switch Proxy	No longer used
307 Temporary Redirect	The requested page has moved temporarily to a new URL
308 Resume Incomplete	Used in the resumable requests proposal to resume aborted PUT or POST requests

4xx: Client Error

Message:	Description:

400 Bad Request	The request cannot be fulfilled due to bad syntax
401 Unauthorized	The request was a legal request, but the server is refusing to respond to it. For use when authentication is possible but has failed or not yet been provided
402 Payment Required	Reserved for future use
403 Forbidden	The request was a legal request, but the server is refusing to respond to it
404 Not Found	The requested page could not be found but may be available again in the future
405 Method Not Allowed	A request was made of a page using a request method not supported by that page
406 Not Acceptable	The server can only generate a response that is not accepted by the client
407 Proxy Authentication Required	The client must first authenticate itself with the proxy
408 Request Timeout	The server timed out waiting for the request
409 Conflict	The request could not be completed because of a conflict in the request
410 Gone	The requested page is no longer available
411 Length Required	The "Content-Length" is not defined. The server will not accept the request without it
412 Precondition Failed	The precondition given in the request evaluated to false by the server
413 Request Entity Too Large	The server will not accept the request, because the request entity is too large
414 Request-URI Too Long	The server will not accept the request, because the URL is too long. Occurs when you convert a POST request to a GET request with a long query information
415 Unsupported Media Type	The server will not accept the request, because the media type is not supported
416 Requested Range Not Satisfiable	The client has asked for a portion of the file, but the server cannot supply that portion
417 Expectation Failed	The server cannot meet the requirements of the Expect request-header field

5xx: Server Error

Message:	Description:

500 Internal Server Error	A generic error message, given when no more specific message is suitable
501 Not Implemented	The server either does not recognize the request method, or it lacks the ability to fulfill the request
502 Bad Gateway	The server was acting as a gateway or proxy and received an invalid response from the upstream server
503 Service Unavailable	The server is currently unavailable (overloaded or down)
504 Gateway Timeout	The server was acting as a gateway or proxy and did not receive a timely response from the upstream server
505 HTTP Version Not Supported	The server does not support the HTTP protocol version used in the request
511 Network Authentication Required	The client needs to authenticate to gain network access

1992

This is a historic document and is not accurate anymore. For up-to-date details on the HTTP specification, see the latest HTTP/1.1 drafts

Status codes

The values of the numeric status code to HTTP requests are as follows. The data sections of messages Error, Forward and redirection responses may be used to contain human-readable diagnostic information.

Success 2xx

These codes indicate success. The body section if present is the object returned by the request. It is a MIME format object. It is in MIME format, and may only be in text/plain, text/html or one fo the formats specified as acceptable in the request.

OK 200

The request was fulfilled.

CREATED 201

Following a POST command, this indicates success, but the textual part of the response line indicates the URI by which the newly created document should be known.

Accepted 202

The request has been accepted for processing, but the processing has not been completed. The request may or may not eventually be acted upon, as it may be disallowed when processing actually takes place. there is no facility for status returns from asynchronous operations such as this.

Partial Information 203

When received in the response to a GET command, this indicates that the returned metainformation is not a definitive set of the object from a server with a copy of the object, but is from a private overlaid web. This may include annotation information about the object, for example.

No Response 204

Server has received the request but there is no information to send back, and the client should stay in the same document view. This is mainly to allow input for scripts without changing the document at the same time.

Error 4xx, 5xx

The 4xx codes are intended for cases in which the client seems to have erred, and the 5xx codes for the cases in which the server is aware that the server has erred. It is impossible to distinguish these cases in general, so the difference is only informational.

The body section may contain a document describing the error in human readable form. The document is in MIME format, and may only be in text/plain, text/html or one for the formats specified as acceptable in the request.

Bad request 400

The request had bad syntax or was inherently impossible to be satisfied.

Unauthorized 401

The parameter to this message gives a specification of authorization schemes which are acceptable. The client should retry the request with a suitable Authorization header.

PaymentRequired 402

The parameter to this message gives a specification of charging schemes acceptable. The client may retry the request with a suitable ChargeTo header.

Forbidden 403

The request is for something forbidden. Authorization will not help.

Not found 404

The server has not found anything matching the URI given

Internal Error 500

The server encountered an unexpected condition which prevented it from fulfilling the request.

Not implemented 501

The server does not support the facility required.

Service temporarily overloaded 502 (TO BE DISCUSSED)

The server cannot process the request due to a high load (whether HTTP servicing or other requests). The implication is that this is a temporary condition which maybe alleviated at other times.

Gateway timeout 503 (TO BE DISCUSSED)

This is equivalent to Internal Error 500, but in the case of a server which is in turn accessing some other service, this indicates that the respose from the other service did not return within a time that the gateway was prepared to wait. As from the point of view of the clientand the HTTP transaction the other service is hidden within the server, this maybe treated identically to Internal error 500, but has more diagnostic value.

Note: The 502 and 503 codes are new and for discussion, September 19, 1994

Redirection 3xx

The codes in this section indicate action to be taken (normally automatically) by the client in order to fulfill the request.

Moved 301

The data requested has been assigned a new URI, the change is permanent. (N.B. this is an optimisation, which must, pragmatically, be included in this definition. Browsers with link editing capabiliy should automatically relink to the new reference, where possible)

The response contains one or more header lines of the form

 URI: String CrLf

Which specify alternative addresses for the object in question. The String is an optional comment field. If the response is to indicate a set of variants which each correspond to the requested URI, then themultipart/alternative wrapping may be used to distinguish different sets

Found 302

The data requested actually resides under a different URL, however, the redirection may be altered on occasion (when making links to these kinds of document, the browser should default to using the Udi of the redirection document, but have the option of linking to the final document) as for "Forward".

The response format is the same as for Moved .

Method 303

Method: body-section

Note: This status code is to be specified in more detail. For the moment it is for discussion only.

Like the found response, this suggests that the client go try another network address. In this case, a different method may be used too, rather than GET.

The body-section contains the parameters to be used for the method. This allows a document to be a pointer to a complex query operation.

The body may be preceded by the following additional fields as listed.

Not Modified 304

If the client has done a conditional GET and access is allowed, but the document has not been modified since the date and time specified in If-Modified-Since field, the server responds with a 304 status code and does not send the document body to the client.

Response headers are as if the client had sent a HEAD request, but limited to only those headers which make sense in this context. This means only headers that are relevant to cache managers and which may have changed independently of the document`s Last-Modified date. Examples include Date , Server and Expires .

The purpose of this feature is to allow efficient updates of local cache information (including relevant metainformation) without requiring the overhead of multiple HTTP requests (e.g. a HEAD followed by a GET) and minimizing the transmittal of information already known by the requesting client (usually a caching proxy).