These diagnostic error messages may be displayed when attempting to access files on a web server or in server log files. Not all messages indicate a fault. The majority are unlikely to appear in a web browser.
100 Continue: a partial request has been received and the client should continue with the request.
101 Switching protocols: the server is switching protocols.
200 OK: The request was completed successfully.
201 Created: the request is complete, and a new resource is created following user input.
202 Accepted: the request was accepted for processing, but processing is not complete.
203 Non-authoritative Information:
204 No Content or File Contains No Data: the server completed the request but nothing is displayed, due to an empty file or syntax error in the document.
205 Reset Content
206 Partial Content:
300 Multiple Choices: the server provides a list of user-selectable alternative links (maximum 5).
301 Moved Permanently: The requested page has moved permanently 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:
305 Use Proxy:
306 Not allocated.
307 Temporary Redirect:
400 Bad File Request: the server did not understand the request, usually caused by incorrect syntax in the URL requested such as substitution of uppercase instead of lowercase character or incorrect punctuation.
401 Unauthorized: usually means that the server requires an encryption key or password from the client which has not been provided (correctly).
402 Payment Required: not currently implimented.
403 Forbidden/Access Denied or Connection Refused by Host: the administrator doesn't want you to view files in this location or a password is required.
404 File Not Found: the server can't find the requested file, because it has been moved, deleted or the wrong name was provided. Either correct the address or delete text in the address back to each backslash in turn until a readable page is found.
406 Not Acceptable: the server can only generate a response that is not accepted by the client.
407 Proxy Authentication Required: this request must be authenticated by a proxy server before it can be served.
408 Request Timeout: the client stopped the request before the server finished retrieving the file or the request took longer than the server was prepared to wait.
409 Conflict: the request could not be completed because of a conflict.
410 Gone: the file requested is no longer available and no forwarding address is available.
411 Length Required: the server will not accept the request because the "Content-Length" is not defined.
412 Precondition Failed: the precondition given in the request was evaluated to false by the server.
413 Request Entity Too Large: the server will not accept the request, because the requested entity is larger than the server is able or willing to process. The server may close the connection.
414 Request-url Too Long: the server will not accept the request, because the url is longer than the server can handle. This can happen with a long query string from user input.
415 Bad File Request: server does not support the file type, media or other coding that the client requested.
416 Requested Range Not Satisfiable:
417 Expectation Failed: the client sent an "expect" request that can not be satisfied by the server.
500 Internal Error: an unexpected server-side problem prevented retrieval of the file. Press "reload" or contact site administrator.
501 Not implemented: the web server doesn't support the function requested.
502 Service Temporarily Overloaded: too many users requesting files at one time. Try again later.
503 Service Unavailable: the server is too busy, the site has moved or your dial-up connection was disonnected.
504 Gateway Timeout: usually the result of a slow or poor connection which the server times out to prevent congestion.
505 HTTP Version not supported: the server can or will not support the version of the HTTP protocol used in the request.
Failed DNS Lookup: the Domain Name Server can't translate your domain request into a valid Internet address. Usually means that the server is too busy or down, or an incorrect URL was entered.
Host Unavailable: usually means that the host is server down. Press "reload" or return to the site later.
Unable to Locate Host: usually means that the host server is down or that the Internet connection is lost or poor so that the domain servers can't be reached. Sometimes the result of an incorrectly provided URL.
Network Connection Refused by Server: usually means that the Web server is too busy.