4xx Client Error
404 Error on German Wikipedia
In a situation where a client appears to have made a mistake, the 4xx class of status codes is used. The server should offer an explanation of the error and note whether the condition is permanent or temporary except when responding to a HEAD request. Regardless of the method of request, these status codes are appropriate. The user agent should reveal any included entity to the user .
400 Bad Request
This indicates that the server either will not or cannot process a request due to an error on the client’s part. For example, this could include deceptive request routing, too large size, malformed request syntax, or invalid request message framing .
401 Unauthorized (RFC 72350)
Although similar to 403 Forbidden, 401 Unauthorized is exclusively used when authentication is necessary and it has either not been provided or failed. The request must include a WWW-Authenticate header field that contains a challenge pertinent to the resource being requested. Semantically, 401 means “unauthenticated” or the user lacks the needed credentials . See Digital and Basic digital access authentication .
Be aware that some sites deliver HTTP401 if an IP address has been banned from the website (usually the website domain) and the address has been denied permission to enter a website.
402 Payment Required
In the beginning, this code was meant to be used as part of some type of micropayment or digital cash scheme, but this never materialized. Instead, the code isn’t used, but is reserved for future use. If a specific developer has exceeded their daily limit of requests, Google Developers API will use this status .
When a server is refusing to respond to a valid request, this status will appear. It may indicate the user is logged in but lacks the required permissions for the resource .
404 Not Found
While it may be available in the future, the resource being requested can’t currently be found. Client’s repeated requests are permitted .
405 Method Not Allowed
In this case, the request method isn’t supported for the requested resource. For example, a GET request on a form that necessitates data be given via POST or a PUT request on a read-only resource.
406 Not Acceptable
According to the Accept headers sent in the request, the resource being requested can only produce content and not accept it . See Content negotiation.
407 Proxy Authentication Required (RFC 7235)
Before going any further, the client must authenticate itself with the proxy .
408 Request Time-out
This indicates that while waiting for the request, the server timed out. Based on HTTP specifications, “The client did not produce a request within the time that the server was prepared to wait.” At a later time, the client MAY duplicate the request without making any changes .
This means that due to some type of conflict in the request, the request was unable to be processed. For example, an edit conflict between numerous simultaneous updates.
This means that the resource being requested isn’t available and will not be in the future. This is only used when a resource has been purposely deleted and the resource needs to be purged. If a client receives a 410 status code, they shouldn’t repeat the request in the future. Clients, including search engines, should eradicate the resource from their indices . Typically, a “404 Not Found” will appear.
411 Length Required
This indicates that the request failed to specify its content’s length, which is mandatory by the resource being requested .
412 Precondition Failed (RFC 7232)
The requester has put conditions on the request and the server doesn’t meet them .
413 Payload Too Large
In the past, this was referred to as “Request Entity Too Large.” It simply means the request is bigger than the server can or will process .
414 URL Too Long
The server was unable to process the provided URL because of its length. This is usually caused by too much data being encoded as a query-string of a GET request. It should be converted to a POST request . In the past, this was referred to as “Request URL Too Long.”
415 Unsupported Media Type
The resource or server doesn’t support the media type of the request entity. For example, when a client uploads an image as image/svg+xml, but the server requires images have a different format.