AWS Error : None of these Availability Zones contains a healthy target. Requests are being routed to all targets. in AWS

Question

I have created a Application Load Balance in Aws. I have created 2 EC2 and make them a group. After that I add that group to the ALB with listener 80.

But when the syste

Answer 1

Ensure that communication is allowed at security group level between your load balancer and your targets.

From AWS https://docs.aws.amazon.com/elasticloadbalancing/latest/application/load-balancer-update-security-groups.html

You must ensure that your load balancer can communicate with registered targets on both the listener port and the health check port [...] you must verify that the security groups associated with the load balancer allow traffic on the new port in both directions.

For example, a simple way to portray the rules you would require if you have a PUBLIC FACING load balancer in security group sg-001 and three EC2 targets in another security group sg-002 is as follows: