Variant Also Negotiates

Overview

506 Variant Also Negotiates indicates a server configuration error: in transparent content negotiation, the chosen variant is itself a negotiable resource, so the negotiation falls into a loop.

This is not the client's fault but a server misconfiguration. The transparent-negotiation feature of RFC 2295 is barely used in practice, so this code is very rarely encountered.

When it happens

• A transparent content-negotiation setup where a variant points back to another negotiable resource
• Negotiation targets are misconfigured to reference each other in a loop
• A logical error in the negotiation mapping

Request / Response example

GET /document HTTP/1.1
Host: example.com
Negotiate: trans

HTTP/1.1 506 Variant Also Negotiates
Content-Type: text/plain

A content-negotiation configuration error occurred on the server.

In code

# Point a resource directly at a concrete file, not another negotiable resource
location = /document {
  try_files /document.en.html =404;
}

Notes

• This is a server-side configuration problem, so there is nothing the client can do about it.
• The transparent negotiation of RFC 2295 is almost never deployed on the modern web, making this code exceedingly rare.

Related status codes

Related headers

Specification