402 Payment Required

Client error: the problem lies with the request. Repeating it unchanged will normally fail again.

When a server should send it. The standard still marks it as reserved for future use, with no agreed meaning. Some APIs use it for an unpaid account or an exhausted paid quota; if you do, explain the problem and the fix in the body.

Common causes. An unpaid account, an expired plan or a used up quota on a paid API.

What to do. Check billing on the service's account page.

Browsers and HTTP clients. Browsers show the body like any other error. There is no standard client behaviour.

Google Search. Like every 4xx except 429, it tells Google the content does not exist: an indexed URL is removed from the index, and a new one is not processed. Crawl frequency for the URL gradually drops. Source: Google Search Central, How HTTP status codes, and network and DNS errors affect Google Search.

Caching. Not cacheable by default (RFC 9110 section 15.1 does not list it). A cache stores it only when the response says so with Cache-Control or Expires.

HTTP/1.1 402 Payment Required
Content-Type: text/plain; charset=utf-8

Payment Required

location /example {
    return 402;
}

RewriteEngine On
RewriteRule ^example$ - [R=402,L]

http_response_code(402);
echo 'Payment Required';
exit;

res.writeHead(402, { 'Content-Type': 'text/plain' });
res.end('Payment Required');

# in a view function
return 'Payment Required', 402