HTTP 451 Unavailable For Legal Reasons
Updated Free mock REST & WebSocket APIs
HTTP 451 Unavailable For Legal Reasons — The resource is blocked for legal reasons, such as a court order or government censorship.
- Class
- 4xx Client Error
- Defined in
- RFC 7725
- Official
- Yes (IANA registry)
- Cacheable by default
- No (unless Cache-Control/Expires say so)
- Safe to retry
- Not without changing the request
Try it: get a real 451 response
Our test endpoint answers every request with 451 Unavailable For Legal Reasons.
curl -i https://mockfox.dev/api/status/451Use it in tests, health-check monitors or to see how your client handles a 451. Add ?delay=2000 to slow it down.
What does HTTP 451 mean?
Named after Fahrenheit 451. Used when content is removed or geo-blocked because of legal demands — DMCA takedowns, court orders, sanctions or local censorship laws. The response should explain the demand and may include a Link header with rel="blocked-by" identifying who is enforcing the block. GitHub uses it for repositories taken down by DMCA.
How to fix 451
- Visitors: Reload the page, check the address for typos, and clear the site's cookies. If it persists, the site owner needs to fix it.
- Developers: Read the response body and server logs for details, fix the request (method, headers, body, credentials) and return a clear error message to clients.
Example 451 response
HTTP/1.1 451 Unavailable For Legal Reasons
Link: <https://legal.example.com>; rel="blocked-by"
Content-Type: application/json
{"status":451,"error":"Unavailable For Legal Reasons"}4xx Client Error: The request contains an error or can't be fulfilled — fix the request before retrying. See the full list of HTTP status codes.
Related status codes
- 403 ForbiddenThe server understood the request but refuses to authorize it.
- 404 Not FoundThe server can't find anything at the requested URL.
- 410 GoneThe resource used to exist but was removed on purpose and won't come back.
Related tools
Frequently asked questions
What does HTTP 451 Unavailable For Legal Reasons mean?
The resource is blocked for legal reasons, such as a court order or government censorship.
Is 451 a client or a server error?
451 is a 4xx code, so it signals a problem with the request (as seen by the server). Retrying the identical request usually gives the same result.
Where is 451 defined?
In RFC 7725. It's listed in the IANA HTTP Status Code Registry.
How can I test how my app handles a 451?
Call https://mockfox.dev/api/status/451 — it responds with 451 to any method, with CORS enabled. Add ?delay=2000 to simulate a slow response.