Takeaways
The server has an internal configuration error: the chosen variant resource is configured to engage in transparent content negotiation itself, and is therefore not a proper end point in the negotiation process.
Information
The 506 Variant Also Negotiates response status code may be given in the context of Transparent Content Negotiation. This protocol enables a client to retrieve the best variant of a given resource, where the server supports multiple variants.
The Variant Also Negotiates status code indicates an internal server configuration error in which the chosen variant is itself configured to engage in content negotiation, so is not a proper negotiation endpoint.