HTTP 1.1 Status Codes
Code Description
1xx Informational Codes
100 Continue: The client SHOULD continue with its request. This interim response is used to inform the client that the initial part of the request has been received and has not yet been rejected by the server.
101 Switching Protocols: The server understands and is willing to comply with the client's request, via the Upgrade message header field, for a change in the application protocol being used on this connection.
2xx Success Codes. This class of status code indicates that the client's request was successfully received, understood, and accepted.
200 OK: The request has succeeded. The information returned with the response is dependent on the method used in the request, for example:
  • GET an entity corresponding to the requested resource is sent in the response;
  • HEAD the entity-header fields corresponding to the requested resource are sent in the response without any message-body;
  • POST an entity describing or containing the result of the action;
  • TRACE an entity containing the request message as received by the end server.
201 Created: The request has been fulfilled and resulted in a new resource being created.
202 Accepted: The request has been accepted for processing, but the processing has not been completed. The request might or might not eventually be acted upon, as it might be disallowed when processing actually takes place.
203 Non-Authoritative Information: The returned metainformation in the entity-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 does not need to return an entity-body, and might want to return updated metainformation.
205 Reset Content: The server has fulfilled the request and the user agent SHOULD reset the document view which caused the request to be sent.
206 Partial Content: The server has fulfilled the partial GET request for the resource.
3xx Redirection: This class of status code indicates that further action needs to be taken by the user agent in order to fulfill the request.
301 Moved Permanently: The requested resource has been assigned a new permanent URI and any future references to this resource SHOULD use one of the returned URIs.
302 Found: The requested resource resides temporarily under a different URI.
303 See Other: The response to the request can be found under a different URI and SHOULD be retrieved 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, the server SHOULD respond with this status code.
305 Use Proxy: The requested resource MUST be accessed through the proxy given by the Location field.
307 Temporary Redirect: The requested resource resides temporarily under a different URI.
4xx Client Error Codes. The 4xx class of status code is intended for cases in which the client seems to have erred.
400 Bad Request: The request could not be understood by the server due to malformed syntax.
401 Unauthorized: The request requires user authentication.
402 Payment Required: This code is reserved for future use.
403 Forbidden: The server understood the request, but is refusing to fulfill it. Authorization will not help and the request SHOULD NOT be repeated.
404 Not Found: The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent.
405 Method Not Allowed: The method specified in the Request-Line is not allowed for the resource identified by the Request-URI.
406 Not Acceptable: The resource identified by the request is only capable of generating response entities which have content characteristics not acceptable according to the accept headers sent in the request.
407 Proxy Authentication Required: This code is similar to 401 (Unauthorized), but indicates that the client must first authenticate itself with the proxy.
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 Length Required: The server refuses to accept the request without a defined Content- Length.
412 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 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 Request-URI Too Long: The server is refusing to service the request because the Request-URI is longer than the server is willing to interpret.
415 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 Requested Range Not Satisfiable
417 Expectation Failed: The expectation given in an Expect request-header field could not be met by this server, or, if the server is a proxy, the server has unambiguous evidence that the request could not be met by the next-hop server.
500 Internal Server Error: The server encountered an unexpected condition which 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, while acting as a gateway or proxy, received an invalid response from the upstream server it accessed in attempting to fulfill the request.
503 Service Unavailable: The server is currently unable to handle the request due to a temporary overloading or maintenance of the server.
504 Gateway Timeout: The server, while acting as a gateway or proxy, did not receive a timely response from the upstream server specified by the URI (e.g. HTTP, FTP, LDAP) or some other auxiliary server (e.g. DNS) it needed to access in attempting to complete the request.
505 HTTP Version Not Supported: The server does not support, or refuses to support, the HTTP protocol version that was used in the request message.

Source: W3C, Hypertext Transfer Protocol -- HTTP/1.1, RFC 2616 Fielding, et al., Status Code Definitions