411 Length Required

The server needs a Content-Length header and the request had none.

Code: 411
Reason phrase: Length Required
Class: 4xx Client error
Defined in: RFC 9110 section 15.5.12
Cacheable by default: No

What it means

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

Common causes. Some clients sending a POST body without stating its length.

What to do. Send the Content-Length header.

How clients and crawlers treat 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.

Example response

HTTP/1.1 411 Length Required
Content-Type: text/plain; charset=utf-8

Length Required

How to send 411

nginx

location /example {
    return 411;
}

Apache (.htaccess)

RewriteEngine On
RewriteRule ^example$ - [R=411,L]

PHP

http_response_code(411);
echo 'Length Required';
exit;

Node.js

res.writeHead(411, { 'Content-Type': 'text/plain' });
res.end('Length Required');

Python (Flask)

# in a view function
return 'Length Required', 411

Change the paths to suit. In nginx, add_header needs always to apply to error responses.

Related codes

All status codes · All 4xx codes

Names and numbers from the IANA HTTP Status Code Registry. Google Search behaviour as documented by Google Search Central.