How to fix IngressClass not found in Kubernetes

Run kubectl get ingressclass to list all available IngressClass resources. If the list is empty, no Ingress controller is installed. Check what you referenced in your Ingress: kubectl get ingress -A -o jsonpath="{.items[*].spec.ingressClassName}" to see all configured class names.

Using Helm is the easiest method:

helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx
helm repo update
helm install nginx-ingress ingress-nginx/ingress-nginx \
  --namespace ingress-nginx \
  --create-namespace

This automatically creates an IngressClass named "nginx". Verify: kubectl get ingressclass. For other controllers (Traefik, HAProxy, etc.), check their official documentation for Helm charts or manifests.

If your Ingress controller is running but IngressClass doesn't exist, create it:

apiVersion: networking.k8s.io/v1
kind: IngressClass
metadata:
  name: nginx
spec:
  controller: k8s.io/ingress-nginx

Save as ingressclass.yaml and apply: kubectl apply -f ingressclass.yaml. Verify with kubectl get ingressclass nginx.

Update your Ingress resource to use correct ingressClassName:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: my-ingress
spec:
  ingressClassName: nginx  # Must match your IngressClass name
  rules:
  - host: example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: my-service
            port:
              number: 80

Apply: kubectl apply -f ingress.yaml.

If you have multiple IngressClass objects and omit ingressClassName from Ingress specs, Kubernetes uses the default. Mark one as default:

apiVersion: networking.k8s.io/v1
kind: IngressClass
metadata:
  name: nginx
  annotations:
    ingressclass.kubernetes.io/is-default-class: "true"
spec:
  controller: k8s.io/ingress-nginx

Apply: kubectl apply -f ingressclass.yaml. Now Ingress resources without ingressClassName will use this class.

Check if the controller pods are deployed: kubectl get pods -n ingress-nginx (or your controller namespace). All pods should be Running. If they're CrashLoopBackOff, check logs: kubectl logs -n ingress-nginx <pod-name>. For other controllers, check their namespace (e.g., traefik, kube-system).

Ensure your manifests use apiVersion: networking.k8s.io/v1 (not v1beta1). The v1beta1 API is deprecated in Kubernetes 1.22+ and removed in 1.25+. Check your Kubernetes version: kubectl version --short. If using older versions (pre-1.18), use the annotation method instead: kubernetes.io/ingress.class: nginx (without ingressClassName field).