4xx Client Error Status Codes

4xx status codes are client error responses. They describe requests that are malformed, unauthorized, forbidden, too large, rate limited, or otherwise impossible for the server to process as sent.

This is an educational guide. The pages linked here are documentation pages served as 200 OK, even when the HTTP status code being explained is an error response.

What 4xx means

Client error responses mean the server understood enough of the request to decide that the client must change something before the request can succeed.

Where 4xx responses appear

The request is malformed, missing needed data, or too large.
The user is unauthenticated, unauthorized, or blocked by policy.
The target resource does not exist, has moved, or is legally unavailable.
The request conflicts with current resource state or rate limits.

Implementation notes

Prefer specific 4xx responses so clients know what to change.
Use 401 for missing or failed authentication and 403 for authenticated requests that are still forbidden.
Use 404 for missing resources and 410 when the removal is intentional and permanent.

Common 4xx groups

Request syntax and validation: 400, 411, 413, 422
Authentication and authorization: 401, 403, 407
Missing, removed, or blocked resources: 404, 410, 451
Rate limits and timing: 408, 425, 429

All 4xx status codes

Code	Name	Meaning
400	Bad Request	The server cannot or will not process the request due to an apparent client error (e.g., malformed request syntax, size too large, invalid request message framing, or deceptive request routing).
401	Unauthorized	Similar to 403 Forbidden, but specifically for use when authentication is required and has failed or has not yet been provided. The response must include a WWW-Authenticate header field containing a challenge applicable to the requested resource. See Basic access authentication and Digest access authentication. 401 semantically means "unauthorised", the user does not have valid authentication credentials for the target resource. Note: Some sites incorrectly issue HTTP 401 when an IP address is banned from the website (usually the website domain) and that specific address is refused permission to access a website.
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, as proposed, for example, by GNU Taler, but that has not yet happened, and this code is not widely used. Google Developers API uses this status if a particular developer has exceeded the daily limit on requests. Sipgate uses this code if an account does not have sufficient funds to start a call. Shopify uses this code when the store has not paid their fees and is temporarily disabled. Stripe uses this code for failed payments where parameters were correct, for example blocked fraudulent payments.
403	Forbidden	The request contained valid data and was understood by the server, but the server is refusing action. This may be due to the user not having the necessary permissions for a resource or needing an account of some sort, or attempting a prohibited action (e.g. creating a duplicate record where only one is allowed). This code is also typically used if the request provided authentication by answering the WWW-Authenticate header field challenge, but the server did not accept that authentication. The request should not be repeated.
404	Not Found	The requested resource could not be found but may be available in the future. Subsequent requests by the client are permissible.
405	Method Not Allowed	A request method is not supported for the requested resource; for example, a GET request on a form that requires data to be presented via POST, or a PUT request on a read-only resource.
406	Not Acceptable	The requested resource is capable of generating only content not acceptable according to the Accept headers sent in the request. See Content negotiation.
407	Proxy Authentication Required	The client must first authenticate itself with the proxy.
408	Request Timeout	The server timed out waiting for the request. According to 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."
409	Conflict	Indicates that the request could not be processed because of conflict in the current state of the resource, such as an edit conflict between multiple simultaneous updates.
410	Gone	Indicates that the resource requested is no longer available and will not be available again. This should be used when a resource has been intentionally removed and the resource should be purged. Upon receiving a 410 status code, the client should not request the resource in the future. Clients such as search engines should remove the resource from their indices.Most use cases do not require clients and search engines to purge the resource, 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 resource.
412	Precondition Failed	The server does not meet one of the preconditions that the requester put on the request header fields.
413	Payload Too Large	The request is larger than the server is willing or able to process. Previously called "Request Entity Too Large".
414	URI Too Long	The URI provided was too long for the server to process. Often the result of too much data being encoded as a query-string of a GET request, in which case it should be converted to a POST request. Called "Request-URI Too Long" previously.
415	Unsupported Media Type	The request entity has a media type which the server or resource does not support. For example, the client uploads an image as image/svg+xml, but the server requires that images use a different format.
416	Range Not Satisfiable	The client has asked for a portion of the file (byte serving), 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. Called "Requested Range Not Satisfiable" previously.
417	Expectation Failed	The server cannot meet the requirements of the Expect request-header field.
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. The RFC specifies this code should be returned by teapots requested to brew coffee. This HTTP status is used as an Easter egg in some websites, such as Google.com's I'm a teapot easter egg.[53]
421	Misdirected Request	The request was directed at a server that is not able to produce a response (for example because of connection reuse).
422	Unprocessable Entity	The request was well-formed but was unable to be followed due to semantic errors.
423	Locked	The resource that is being accessed is locked.
424	Failed Dependency	The request failed because it depended on another request and that request failed (e.g., a PROPPATCH).
425	Too Early	Indicates that the server is unwilling to risk processing a request that might be replayed.
426	Upgrade Required	The client should switch to a different protocol such as TLS/1.3, given in the Upgrade header field.
428	Precondition Required	The origin server requires the request to be conditional. Intended to prevent 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.
429	Too Many Requests	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	The server is unwilling to process the request because either an individual header field, or all the header fields collectively, are too large.
451	Unavailable For Legal Reasons	A server operator has received a legal demand to deny access to a resource or to a set of resources that includes the requested resource. The code 451 was chosen as a reference to the novel Fahrenheit 451 (see the Acknowledgements in the RFC).