default backend - 404 ☸️ Kubernetes

Ingress returns "404 Not Found" / "default backend - 404" (ingress-nginx)

The ingress controller received the request but no Ingress rule matched the host/path, so it answered with its default backend.

Seen on: Kubernetes

Meaning

ingress-nginx serves a 404 page when the Host header or path doesn’t match any rule, the Ingress lacks the right ingressClassName (so this controller ignores it), or the path type/rewrite doesn’t match the URL.

Common causes

  • Missing or wrong ingressClassName (controller ignores the Ingress)
  • Host in the rule differs from the requested host (www vs apex)
  • pathType/Prefix vs Exact mismatch or missing rewrite
  • Ingress in another namespace from the Service it references

⚡ Quick fix

  1. kubectl get ingress -A and check CLASS and HOSTS
  2. Request with the exact host: curl -H 'Host: app.example.com'
  3. Check controller logs for the request

Detailed fix by platform

YAML

  1. bash
    spec:
  ingressClassName: nginx
  rules:
  - host: app.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend: { service: { name: web, port: { number: 80 } } }

How to diagnose

  1. Class — ingressClassName matches the controller?
  2. Host — Exact match?
  3. Logs — kubectl logs -n ingress-nginx deploy/ingress-nginx-controller

🔧 Still not fixed?

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