400 Bad Request
The server cannot or will not process the request due to an apparent client error.
401 Unauthorized
Similar to 403 Forbidden, but specifically for use when authentication is required and has failed or has not yet been provided.
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.
403 Forbidden
The request was valid, but the server is refusing action. The user might not have the necessary permissions for a resource.
404 Not Found
The requested resource could not be found but may be available in the future.
405 Method Not Allowed
A request method is not supported for the requested resource.
406 Not Acceptable
The requested resource is capable of generating only content not acceptable according to the Accept headers sent in the request.
407 Proxy Authentication Required
The client must first authenticate itself with the proxy.
408 Request Timeout
The server timed out waiting for the request.
409 Conflict
Indicates that the request could not be processed because of conflict in the request, such as an edit conflict.
410 Gone
Indicates that the resource requested is no longer available and will not be available again.
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.
413 Payload Too Large
The request is larger than the server is willing or able to process.
414 URI Too Long
The URI provided was too long for the server to process.
415 Unsupported Media Type
The request entity has a media type which the server or resource does not support.
416 Range Not Satisfiable
The client has asked for a portion of the file, but the server cannot supply that portion.
417 Expectation Failed
The server cannot meet the requirements of the Expect request-header field.
418 I'm a teapot
The server refuses the attempt to brew coffee with a teapot.
421 Misdirected Request
The request was directed at a server that is not able to produce a response.
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 due to failure of a previous request.
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/1.0.
428 Precondition Required
The origin server requires the request to be conditional.
429 Too Many Requests
The user has sent too many requests in a given amount of time.
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.
