4xx Client error
HTTP 451 Unavailable For Legal Reasons
The server denies access to the resource because of a legal demand, such as a court order or a government block. The response should explain the demand, and may name who is enforcing it in a Link header with rel="blocked-by". The number refers to the novel Fahrenheit 451.
Defined in RFC 7725, section 3(opens in a new tab)
//_01 Uptime checks
Is 451 up or down for a monitor?
Uptimecheck HTTP monitor
Default settings
Down. It is outside the default 200–399 range, so a monitor reports an outage once a second check confirms it. If 451 is the answer you expect from that URL, add it to the monitor’s expected status codes.
Is it down? checker
Free, at /is-it-down/
Up. The checker counts any answer below 500 as the site answering: a 451 comes from a server that is running.
//_02 Causes and fixes
Why you see 451 and what to do
Typical causes
- Content blocked in a country by court order or law.
- A site blocking visitors from a region for legal reasons.
If you run the site
- Explain in the page why the content is unavailable, and who required it.
If you’re a visitor
- The content isn’t available where you are.
Know the moment your site stops answering as it should
An Uptimecheck monitor requests your page as often as every minute, checks the status code against the ones you expect, confirms a failure with a second check and then alerts you.
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Questions
What does HTTP 451 mean?
The server denies access to the resource because of a legal demand, such as a court order or a government block. The response should explain the demand, and may name who is enforcing it in a Link header with rel="blocked-by". The number refers to the novel Fahrenheit 451.
Does an uptime monitor count 451 as down?
Down. It is outside the default 200–399 range, so a monitor reports an outage once a second check confirms it. If 451 is the answer you expect from that URL, add it to the monitor’s expected status codes.
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