HTTP 506 — Variant Also Negotiates
HTTP 506 catches a server configuration paradox: transparent content negotiation led to a variant that is itself configured to negotiate, so the server refuses rather than loop.
When 506 shows up
- Misconfigured servers where a negotiation variant doubles as a negotiation endpoint.
- Proxy layers stacking negotiation on negotiation.
Mocking a 506 response
A response with this status can be faked end to end with a local mock rule — no backend changes needed. The configuration below mirrors the rule fields the ApiSimul editor uses (method, path, status, delay in milliseconds, response body):
{
"method": "GET",
"path": "/content/negotiated",
"status": 506,
"delay": 190,
"enabled": true,
"body": null
}Dynamic placeholders such as {{random.name}}, {{string.uuid}} or {{number.int 1 100}} can appear inside the body to vary each response, which keeps client-side list rendering and retry logic honest during development.
Frequently asked questions
What does HTTP 506 mean?
The chosen variant is itself engaged in negotiation, which would loop. It signals a server configuration error, not a client problem.
How can I test a 506 response without a real backend?
Define a mock rule with the method and path your client requests and set the status to 506. The example configuration above returns this response after the listed delay, so the client exercises its 506 handling exactly as it would against a live server.
Related status codes
Need the response in your own project? Spin up rules for any status with the ApiSimul mock server, or browse every status code page.