400 |
Bad Request |
There is a syntax error in the clients request and the request has been denied. |
401 |
Unauthorised |
The requesting header sent by the client did not contain the necessary authentication codes, and the client is denied access. |
402 |
Payment Required Reserved for future use. |
The original intention was that this code might be used as part of some form of digital cash or micropayment scheme, but that has not happened, and this code is not usually used. As an example of its use, however, Apple’s MobileMe service generates a 402 error if the MobileMe account is delinquent. In addition, YouTube uses this status if a particular IP address has made excessive requests, and requires the person to enter a CAPTCHA. |
403 |
Forbidden |
The request was a valid request, but the server is refusing to respond to it. Unlike a 401 Unauthorized response, authenticating will make no difference. On servers where authentication is required, this commonly means that the provided credentials were successfully authenticated but that the credentials still do not grant the client permission to access the file or page (e.g. a recognized user attempting to access that is restricted to their access level). |
404 |
Not Found |
The requested file or page could not be found but may be available again in the future. Possibly because the file or page was deleted, or never existed. Sometimes caused by misspellings of URLs. Subsequent requests by the client are permissible. |
405 |
Method Not Allowed |
A request was made of a file or page using a request method not supported by that file or page for example using a GET on a form which requires data to be presented via POST, or using PUT on a read-only file or page. The method the client is using to access the file is not allowed. |
406 |
Not Acceptable |
The requested file or page is only capable of generating content not acceptable according to the Accept headers sent in the request. The requested file exists but cannot be used as the client system doesn’t understand the format the file is configured for. |
407 |
Proxy Authentication Required |
The requested file or page is only capable of generating content not acceptable according to the Accept headers sent in the request. The requested file exists but cannot be used as the client system doesn’t understand the format the file is configured for. |
408 |
Request Timeout |
The server timed out waiting for the request. According to W3 HTTP specifications: “The client did not produce a request within the time that the server was prepared to wait. The client MAY repeat the request without modifications at any later time.” Request. The server took longer than its allowed time to process the request. Often caused by heavy net traffic. |
409 |
Conflict |
Indicates that the request could not be processed because of a conflict in the request, such as an edit conflict or too many concurrent requests for a single file by the client. |
410 |
Gone |
Indicates that the file or page requested is no longer available and will not be available again. This should be used when a file or page has been intentionally removed and the file or page should be purged. Upon receiving a 410 status code, the client should not request the file or page again in the future. Clients such as search engines should remove the file or page from their indices. Most use cases do not require clients and search engines to purge the file or page, and a “404 Not Found” may be used instead. |
411 |
Length Required |
The request did not specify the length of its content, which is required by the requested file or page. |
412 |
Precondition Failed |
The server does not meet one of the preconditions that the requester put on the request. A certain configuration is required for this file to be delivered, but the client has not set this up. |
413 |
Request Entity Too Large |
The request is larger than the server is willing or able to process. The requested file was too big to process. |
414 |
Request-URI Too Long |
The URI provided was too long for the server to process. The address the client entered was longer than the server is allowed to process. |
415 |
Unsupported Media Type |
The client has a media type which the server does not support. For example, the client attempts to uploads an image as image.xml but the server requires that images use a different format. |
416 |
Requested Range Not Satisfiable |
The client has asked for a portion of the file, but the server cannot supply that portion. For example, if the client asked for a part of the file that lies beyond the end of the file. |
417 |
Expectation Failed |
The server cannot meet the requirements of the Expect request-header field. 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. |
418 |
I’m a teapot |
This code was defined in 1998 as one of the traditional IETF April Fools’ jokes, in RFC 2324, Hyper Text Coffee Pot Control Protocol, and is not expected to be implemented by actual HTTP servers. |
420 |
Enhance Your Calm (Twitter) |
Not part of the HTTP standard, but returned by the Twitter Search and Trends API when the client is being rate limited. Other services may wish to implement the 429 Too Many Requests response code instead. |
422 |
Unprocessable Entity (WebDAV; RFC 4918) |
The request was well-formed but was unable to be followed due to semantic errors or syntax errors. |
423 |
Locked (WebDAV; RFC 4918) |
The file or page that the client is trying to accessed is locked by the server. |
424 |
Failed Dependency (WebDAV; RFC 4918) |
The request could not be performed on the file or page because the requested action depended on another action and that previous action failed. For example, if a command in a PROPPATCH method fails, then, at minimum, the rest of the commands will also fail with 424 (Failed Dependency). |
425 |
Unordered Collection (Internet draft) |
Defined in drafts of “WebDAV Advanced Collections Protocol” not yet in use. |
426 |
Upgrade Required (RFC 2817) |
The client should switch to a different protocol such as TLS/1.0. |
428 |
Precondition Required (RFC 6585) |
The origin server requires the request to be conditional. Its typical use is to avoid the “lost update” problem, where a client GETs a resource’s state, modifies it, and PUTs it back to the server, when meanwhile a third party has modified the state on the server, leading to a conflict. By requiring requests to be conditional, the server can assure that clients are working with the correct copies. |
429 |
Too Many Requests (RFC 6585) |
The user has sent too many requests in a given amount of time. Intended for use with rate limiting schemes. |
431 |
Request Header Fields Too Large (RFC 6585) |
The server is unwilling to process the request because either an individual header field, or all the header fields collectively, are too large. |
432 |
Request Thrashed |
The server has received too many requests and is currently busy trying to handle them, likely causing other problems. The server’s hosed. |
444 |
No Response (Nginx) |
Used in Nginx logs to indicate that the server has returned no information to the client and closed the connection (useful as a deterrent for malware). |
449 |
Retry With (Microsoft) |
A Microsoft extension. The request should be retried after performing the appropriate action. Often search-engines or custom applications will ignore required parameters. Where no default action is appropriate, the Aviongoo website sends a “HTTP/1.1 449 Retry with valid parameters: param1, param2, . . .” response. The applications may choose to learn, or not. |
450 |
Blocked by Windows Parental Controls (Microsoft) |
A Microsoft extension. This error is given when Windows Parental Controls are turned on and are blocking access to the given webpage. |
451 |
Unavailable For Legal Reasons (Internet draft) |
Defined in the internet draft “A New HTTP Status Code for Legally-restricted File or pages”. Intended to be used when file or page access is denied for legal reasons, e.g. censorship or government-mandated blocked access. A reference to the 1953 dystopian novel Fahrenheit 451, where books are outlawed. |
451 |
Redirect (Microsoft) |
Used in Exchange ActiveSync if there either is a more efficient server to use or the server can’t access the users’ mailbox. The client is supposed to re-run the HTTP Autodiscovery protocol to find a better suited server. |
494 |
Request Header Too Large (Nginx) |
Nginx internal code similar to 431 but it was introduced earlier. |
495 |
Cert Error (Nginx) |
Nginx internal code used when SSL client certificate error occurred to distinguish it from 4XX in a log and an error page redirection. |
496 |
No Cert (Nginx) |
Nginx internal code used when client didn’t provide certificate to distinguish it from 4XX in a log and an error page redirection. |
497 |
HTTP to HTTPS (Nginx) |
Nginx internal code used for the plain HTTP requests that are sent to HTTPS port to distinguish it from 4XX in a log and an error page redirection. |
499 |
Client Closed Request (Nginx) |
Used in Nginx logs to indicate when the connection has been closed by client while the server is still processing its request, making server unable to send a status code back. |