Received invalid status code: 404 in the backend server’s HTTP response.

I had configured an azure application gateway with ingress controller and everything looks good i.e

1. Workload is running
2. Service is running
3. Ingress resource deployed

below is the image of 'Backed health'

Service status

Ingress status

Pods status

Below the are yaml snippets used for pods, ingress, service deployment

apiVersion: apps/v1
kind: Deployment
metadata:
name: apiservice-deployment
labels:
app: apiservice
spec:
replicas: 1
selector:
matchLabels:
app: apiservice
template:
metadata:
labels:
app: apiservice
spec:
containers:

• name: apiservice
  image: "{{ .Values.image.repository }}:{{ .Values.image.tag}}"
  ports:
• containerPort: 8080
  protocol: TCP

apiVersion: v1
kind: Service
metadata:
name: apiservice-service
spec:
ports:

• port: 80
  targetPort: 8080
  protocol: TCP
  name: http
  selector:
  app: apiservice
  type: ClusterIP

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: apiservice-ingress
annotations:
kubernetes.io/ingress.class: azure/application-gateway
spec:
rules:

• http:
  paths:
• path: /
  backend:
  service:
  name: apiservice-service
  port:
  number: 80
  pathType: Prefix

Pods, service and ingress showing as green status but Gateways says 'All the instances in one or more backend pool is unhealthy', I can see the below is the backend pool

I am not able to figure our why I am getting the error "502 Bad Gateway" when I am trying to access the app via the public IP "http://20.85.243.181/",
Kindly suggest if I am doing something wrong