10.4 Client Error 4xx


The 4xx class of status code is intended for cases in which the client seems to have erred. Except when responding to a HEAD request, the server SHOULD include an entity containing an explanation of the error situation, and whether it is a temporary or permanent condition. These status codes are applicable to any request method. User agents SHOULD display any included entity to the user.

If the client is sending data, a server implementation using TCP SHOULD be careful to ensure that the client acknowledges receipt of the packet(s) containing the response, before the server closes the input connection. If the client continues sending data to the server after the close, the server's TCP stack will send a reset packet to the client, which may erase the client's unacknowledged input buffers before they can be read and interpreted by the HTTP application.
1.   400 Bad Request ... 10.4.1  
2.   401 Unauthorized ... 10.4.2  
3.   402 Payment Required ... 10.4.3  
4.   403 Forbidden ... 10.4.4  
5.   404 Not Found ... 10.4.5  
6.   405 Method Not Allowed ... 10.4.6  
7.   406 Not Acceptable ... 10.4.7  
8.   407 Proxy Authentication Required ... 10.4.8  
9.   408 Request Timeout ... 10.4.9  
10.   409 Conflict ... 10.4.10  
11.   410 Gone ... 10.4.11  
12.   411 Length Required ... 10.4.12  
13.   412 Precondition Failed ... 10.4.13  
14.   413 Request Entity Too Large ... 10.4.14  
15.   414 Request-URI Too Long ... 10.4.15  
16.   415 Unsupported Media Type ... 10.4.16  
17.   416 Requested Range Not Satisfiable ... 10.4.17  
18.   417 Expectation Failed ... 10.4.18