400-499

Client error responses

The HTTP status codes in the range 400 to 499 are client error codes. They are used by the server to tell the client that the request failed due to an error by the client. Request itself was invalid or the client did not have the necessary permissions to access the requested resource. They are commonly used by web applications and APIs to indicate problems with request processing. It is important to note that some of these codes can also help the client diagnose and fix the error. For example, the 400 code indicates that the client's request is in error and can help the client determine the cause of the error. The 401 code tells the client that authentication is required to access the requested resource, while the 403 code indicates that the client does not have permission to access the resource.

<400/> Bad Request

The request is invalid
Official Substatus codes

<401/> Unauthorized

The request was unauthorized
Official Substatus codes

<402/> Payment Required

a payment is required
Official

<403/> Forbidden

This request is not allowed
Official Substatus codes

<404/> Not Found

The web server could not find the requested resource
Official Substatus codes

<405/> Method Not Allowed

The method used for the request is not allowed
Official Substatus codes

<406/> Not Acceptable

The user agent does not have an accepted representation
Official Substatus codes

<407/> Proxy Authentication Required

Authentication with the proxy is required
Official

<408/> Request Timeout

The time for the request has expired
Official

<409/> Conflict

There was a conflict at the current state of ressouce
Official

<410/> Gone

The ressouce is permanently unavailable and was probably deleted
Official

<411/> Length Required

The request was not processed because a content length was expected
Official

<412/> Precondition Failed

Pre-conditions were not satisfactory, the request was not successful
Official Substatus codes

<413/> Payload Too Large

The payload is too big for the server
Official

<414/> URI Too Long

The URL is too long, the server is not ready to evaluate it
Official

<415/> Unsupported Media Type

The format of the payload is not available for the ressouce
Official

<416/> Range Not Satisfiable

The requested areas cannot be provided
Official

<417/> Expectation Failed

The expectations could not be met
Official

<418/> I'm a teapot

The coffee could not be made with a teapot
Official

<421/> Misdirected Request

The request was misdirected
Official

<422/> Unprocessable Content

Due to a semantic error, the request could not be processed
Official

<423/> Locked

The ressouce is locked
Official

<424/> Failed Dependency

There is no indispensable dependence
Official

<425/> Too Early

Server does not want to process the request yet
Official

<426/> Upgrade Required

An upgrade of the protocol is required
Official

<428/> Precondition Required

A precondition is required to process the request
Official

<429/> Too Many Requests

The server has received too many requests
Official

<431/> Request Header Fields Too Large

The request header is too large
Official

<440/> Login Time-out

the client's HTTP session has expired and he needs to log in again
Unofficial (Microsoft Internet Information Services)

<444/> No Response

Used internally to instruct the server not to return any information to the client and to close the connection immediately
Unofficial (nginx)

<449/> Retry With

Status code indicates that the request cannot be fulfilled because the customer has not provided enough information
Unofficial (Microsoft Internet Information Services)

<451/> Unavailable For Legal Reasons

Due to legal reasons the request has been rejected
Official

<451/> Redirect

the user's mailbox could not be reached
Unofficial (Microsoft Internet Information Services)

<494/> Request header too large

The client has either sent a too large HTTP request or the transmitted HTTP headers are too long
Unofficial (nginx)

<495/> SSL Certificate Error

an error occurred during the verification of the client certificate
Unofficial (nginx)

<496/> SSL Certificate Required

Request that does not contain an SSL certificate, although one is required
Unofficial (nginx)

<497/> HTTP Request Sent to HTTPS Port

a regular HTTP request was sent to the HTTPS port
Unofficial (nginx)

<499/> Client Closed Request

the client closed the request before the server could send a response
Unofficial (nginx)