**Important:** the custom backend must return the correct HTTP status code to be returned. NGINX do not changes the response from the custom default backend.
Using this two headers is possible to use a custom backend service like [this one](https://github.com/kubernetes/ingress-nginx/tree/master/examples/customization/custom-errors/nginx) that inspect each request and returns a custom error page with the format expected by the client. Please check the example [custom-errors](examples/customization/custom-errors/README.md)