408 Request Timeout

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

When a server should send it. When the client opened a connection but did not finish sending the request in time. Servers send it as they close idle connections, and should add Connection: close.

Common causes. A slow or dropped connection, or a browser keeping an idle connection open too long.

What to do. Retry. Persistent timeouts point to the network or an upload that is too slow.

Browsers and HTTP clients. Browsers that receive it on an idle keep-alive connection retry the request on a new connection automatically, so users rarely see it.

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/1.1 408 Request Timeout
Connection: close

Request Timeout

location /example {
    return 408;
}

RewriteEngine On
RewriteRule ^example$ - [R=408,L]

http_response_code(408);
echo 'Request Timeout';
exit;

res.writeHead(408, { 'Content-Type': 'text/plain' });
res.end('Request Timeout');

# in a view function
return 'Request Timeout', 408