HTTP 506 — Variant Also Negotiates
Transparent content negotiation for the request results in a circular reference
When to use it
Use status 506 when this is the correct HTTP response semantic: Transparent content negotiation for the request results in a circular reference
Request and response example
GET /service HTTP/1.1
Host: api.example.com
HTTP/1.1 506 Variant Also Negotiates
Content-Type: application/json
{"error":"Service failed to process the request"}