506 Variant Also Negotiates

Transparent content negotiation misconfiguration: the chosen variant is itself negotiable.

506 at a glance

Code: 506
Name: Variant Also Negotiates
Class: 5xx Server error
Status: IANA-registered standard code
Defined in: RFC 2295, Section 8.1
Cacheable by default: No by default. Caches store it only when the response carries explicit freshness (Cache-Control max-age, s-maxage or Expires).

What 506 means

506 Variant Also Negotiates (RFC 2295) signals a server configuration error in transparent content negotiation: the variant selected for the client is configured to negotiate again, which would loop. It is experimental and almost never seen.

What typically causes a 506

Misconfigured Apache type maps or MultiViews where a variant points back to a negotiable resource.

Fix it on the server

Make variants concrete resources, not negotiable ones.

Fix it as a client or visitor

Nothing to do on the client side; report it to the site owner.

Headers that go with 506

Header	Role
`Alternates`	RFC 2295 header listing variants.

Example response

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