451 Unavailable For Legal Reasons

The resource is unavailable for legal reasons, such as a court order or government censorship.

451 at a glance

Code: 451
Name: Unavailable For Legal Reasons
Class: 4xx Client error
Status: IANA-registered standard code
Defined in: RFC 7725, Section 3
Cacheable by default: No by default. Caches store it only when the response carries explicit freshness (Cache-Control max-age, s-maxage or Expires).

What 451 means

451 Unavailable For Legal Reasons (RFC 7725) says access is denied because of a legal demand, and the number is a nod to Fahrenheit 451. The response should explain the demand and who made it; a Link header with rel="blocked-by" can identify the entity implementing the block.

What typically causes a 451

Content removed or geo-blocked after court orders, DMCA notices or national blocking laws.
Some US sites geo-blocked EU visitors with 451 when GDPR took effect in 2018.
GitHub returns 451 for repositories disabled due to legal takedowns.

Fix it on the server

Explain which legal demand applies and, where possible, link to it; send Link: <...>; rel="blocked-by".

Fix it as a client or visitor

There is nothing technical to fix; the block is intentional. Lumen Database often has the notice.

Headers that go with 451

Header	Role
`Link`	`rel="blocked-by"` identifies who is blocking.

Example response

HTTP/1.1 451 Unavailable For Legal Reasons
Link: <https://spqr.example.org/legislatione>; rel="blocked-by"
Content-Type: text/html