AJAX - The Complete Reference

600 Part IV: Appendixes

4XX Codes

Status Code Reason String Description

403 Forbidden Request is understood but disallowed and should not be

reattempted, compared to the 401 code, which might

suggest a reauthentication. A typical response code in

response to a query for a directory listing when directory

browsing is disallowed.

404 Not Found Usually issued in response to a typo by the user or a

moved resource, as the server can't find anything that

matches the request nor any indication that the requested

item has been moved.

405 Method Not Allowed Issued in response to a method request such as GET,

POST, or PUT on an object where such a method is not

supported. Generally an indication of what methods that

are supported will be returned.

406 Not Acceptable Indicates that the response to the request will not be

in one of the content types acceptable by the browser,

so why bother doing the request? This is an unlikely

response given the */* acceptance issued by most, if not

all, browsers.

407 Proxy Authentication

Required

Indicates that the proxy server requires some form of

authentication to continue. This code is similar to the

401 code.

408 Request Time-out Indicates that the client did not produce or finish a request

within the time that the server was prepared to wait.

409 Conflict Indicates the request could not be completed because of

a conflict with the requested resource; for example, the

file might be locked.

410 Gone Indicates that the requested object is no longer available

at the server and no forwarding address is known. Search

engines might want to add remote references to objects

that return this value because it is a permanent condition.

411 Length Required Indicates that the server refuses to accept the request

without a defined Content-Length. This might happen

when a file is posted without a length.

412 Precondition Failed Indicates that a precondition given in one or more of the

request header fields, such as If-Unmodified-Since,

evaluated to false.

TABLE B-7 HTTP 1.1 Response Codes and Reason Strings (continued)