413 Content Too Large

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

When a server should send it. When the request body is larger than the server will accept. If the limit is temporary, add Retry-After. Proxies send it too: nginx's client_max_body_size defaults to 1 MB.

Common causes. Uploading a file above the limit, often nginx client_max_body_size or PHP upload_max_filesize.

What to do. Upload a smaller file, or raise the limit on the server.

Browsers and HTTP clients. Browsers show the error page the server or proxy returns. An upload stopped by a proxy often looks like a broken connection in JavaScript, because the server closes it before reading the body.

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/1.1 413 Content Too Large
Content-Type: text/plain; charset=utf-8

Content Too Large

location /example {
    return 413;
}

RewriteEngine On
RewriteRule ^example$ - [R=413,L]

http_response_code(413);
echo 'Content Too Large';
exit;

res.writeHead(413, { 'Content-Type': 'text/plain' });
res.end('Content Too Large');

# in a view function
return 'Content Too Large', 413