HTTP 451 status code

In the computer network field, HTTP 451 Unavailable For Legal Reasons (English: HTTP 451 Unavailable For Legal Reasons) is an error status code of the HTTP protocol. It is determined when the user requests access to a certain website that has been reviewed by government review and other verification methods. This error code will be displayed when the source is illegal.

This status code is defined in RFC 7725 and is different from other status codes in the HTTP protocol.

Definition

According to the definition, the occurrence of HTTP 451 error code status does not mean whether the address exists, but it means that the webpage may be dangerous to national security, or that the Web pages may violate copyright, privacy, blasphemy, or other laws or court orders.

This response code has the following properties:

Unless otherwise specified, this response code can be cached.

Must carry a Link header that lists the URI of the entity requesting to block the address; and should have a "rel" field, the value should be "blocked-by".