404 Checker
HTTP Status Codes
29 Codes Documented
4XX — Client Error
The client appears to have made an error, such as requesting a resource that does not exist (404) or lacking proper authentication (401).
HTTP
400
Bad Request
RFC 9110
This request was not understood or could not be processed by the server due to malformed request syntax, invalid request message framing, or deceptive routing.
HTTP
401
Unauthorized
RFC 9110
Semantically "Unauthenticated". The request requires user authentication credentials that are missing or invalid. The server must provide a WWW-Authenticate header field.
HTTP
402
Payment Required
RFC 9110
Reserved for digital payment schemes. Increasingly utilized by modern paid developer APIs, web monetization standards, and subscription gateways.
HTTP
403
Forbidden
RFC 9110
The server understood the request, but refuses to authorize it. Unlike 401, authentication credentials will not help because the client lacks access privileges to this resource.
HTTP
404
Not Found
RFC 9110
The origin server cannot find a current representation for the target resource or is not willing to disclose that one exists. (If a resource has been permanently removed, 410 "Gone" should be used).
HTTP
405
Method Not Allowed
RFC 9110
The request method is recognized by the server but is not supported by the target resource (e.g., attempting a POST or DELETE on a static file). The response must include an "Allow" header listing permitted methods.
HTTP
406
Not Acceptable
RFC 9110
The target resource does not have a representation matching the client's content negotiation Accept headers (e.g. Accept-Charset, Accept-Language, or Accept MIME types).
HTTP
407
Proxy Authentication Required
RFC 9110
Similar to 401 (Unauthorized), but authentication must be performed with an intermediate proxy mediating access. The proxy must send a Proxy-Authenticate header.
HTTP
408
Request Timeout
RFC 9110
The server timed out waiting for the client to send the complete request. The connection was closed by the server and the client may repeat the request without modification.
HTTP
409
Conflict
RFC 9110
The request could not be completed due to a conflict with the current state of the target resource (e.g., version control merge conflicts or editing an out-of-date resource).
HTTP
410
Gone
RFC 9110
This resource has been permanently removed with no forwarding address. Search engines immediately de-index 410 URLs and do not retry crawling them.
HTTP
411
Length Required
RFC 9110
The server refuses to process the request without a defined Content-Length header. The client may repeat the request by adding a valid Content-Length header field.
HTTP
412
Precondition Failed
RFC 9110
One or more conditions given in the request header fields (such as If-Match or If-Unmodified-Since) evaluated to false when tested on the server.
HTTP
413
Content Too Large
RFC 9110
The server refuses to process the request because the payload body is larger than the server is willing or able to process (formerly "Request Entity Too Large").
HTTP
414
URI Too Long
RFC 9110
The request-target URI is longer than the server is willing to interpret (formerly "Request-URI Too Long"). Commonly caused when form submissions convert large POST bodies into oversized GET query strings.
HTTP
415
Unsupported Media Type
RFC 9110
The origin server refuses to service the request because the payload is in a format not supported by this method on the target resource (e.g. sending XML to an endpoint expecting JSON).
HTTP
416
Range Not Satisfiable
RFC 9110
None of the ranges in the request's Range header field overlap the current extent of the selected resource (e.g. requesting bytes beyond the total file length).
HTTP
417
Expectation Failed
RFC 9110
The expectation given in the request's "Expect" header field (such as Expect: 100-continue) could not be met by the server or its intermediate proxies.
HTTP
418
I'm a teapot
RFC 2324
Proprietary
Defined in 1998 as an IETF April Fools' joke in RFC 2324 (Hyper Text Coffee Pot Control Protocol). The RFC specifies this code should be returned by teapots requested to brew coffee. Famous Easter egg implemented across the web and popular APIs.
HTTP
421
Misdirected Request
RFC 9110
The request was directed at a server that is not able to produce a response (common with HTTP/2 and HTTP/3 connection reuse when a TLS connection does not cover the requested hostname).
HTTP
422
Unprocessable Content
RFC 9110
The server understands the content type of the request entity and the syntax is correct, but was unable to process the contained instructions due to semantic validation errors (formerly "Unprocessable Entity").
HTTP
423
Locked
RFC 4918
The resource that is being accessed is currently locked against modification (WebDAV).
HTTP
424
Failed Dependency
RFC 4918
The request failed because it depended on another action and that action failed (WebDAV).
HTTP
425
Too Early
RFC 8470
Indicates that the server is unwilling to risk processing a request that might be replayed in early data over 0-RTT TLS 1.3 connections.
HTTP
426
Upgrade Required
RFC 9110
The client should switch to a different protocol such as TLS 1.3 or HTTP/2, as specified in the response Upgrade header.
HTTP
428
Precondition Required
RFC 6585
The origin server requires the request to be conditional. Intended to prevent the "lost update" problem where multiple clients modify resource state without synchronization.
HTTP
429
Too Many Requests
RFC 6585
The user has sent too many requests in a given amount of time ("rate limiting"). Often accompanied by a Retry-After header indicating how long to wait before trying again.
HTTP
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.
HTTP
451
Unavailable For Legal Reasons
RFC 7725
Access to the resource is denied due to a legal demand, court order, or government censorship. The code 451 was chosen as an homage to Ray Bradbury's novel Fahrenheit 451.
Codes In This Class
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