EKS clusters should run on a supported Kubernetes version

How to fix it

Upgrade the control plane to a Kubernetes version still on AWS standard support, and to a current release rather than the oldest that passes today: the supported floor moves as AWS retires releases. EKS moves one minor version at a time, so a cluster several releases behind needs one upgrade per release. Each needs up to five free IPs in the cluster's subnets, cannot be rolled back after seven days, and breaks workloads calling an API the target release removed.

In the console

EKS → Clusters → the cluster → Upgrade now

With the AWS CLI

aws eks update-cluster-version --name <cluster-name> --kubernetes-version <version> --region <region>

With Terraform

resource "aws_eks_cluster" "this" {
  name     = "example"
  role_arn = aws_iam_role.eks_cluster.arn
  version  = var.kubernetes_version

  vpc_config {
    subnet_ids = var.private_subnet_ids
  }
}