506 Variant Also Negotiates

The server's content negotiation is misconfigured and loops.

Code: 506
Reason phrase: Variant Also Negotiates
Class: 5xx Server error
Defined in: RFC 2295 section 8.1
Cacheable by default: No

What it means

Server error: the request may be fine, but the server failed to carry it out.

Common causes. A server configuration mistake.

What to do. Site owners should fix the negotiation settings.

How clients and crawlers treat it

Google Search. Googlebot treats 5xx responses as a sign of trouble and temporarily slows its crawl rate. Already indexed URLs are kept at first, but are dropped if the errors continue. 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/1.1 506 Variant Also Negotiates
Content-Type: text/plain; charset=utf-8

Variant Also Negotiates

How to send 506

nginx

location /example {
    return 506;
}

Apache (.htaccess)

RewriteEngine On
RewriteRule ^example$ - [R=506,L]

PHP

http_response_code(506);
echo 'Variant Also Negotiates';
exit;

Node.js

res.writeHead(506, { 'Content-Type': 'text/plain' });
res.end('Variant Also Negotiates');

Python (Flask)

# in a view function
return 'Variant Also Negotiates', 506

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

Related codes

All status codes · All 5xx codes

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