Ubuntu 20.04 Kubernetes 1.26 incompatibility

UPDATE 2023–03–18

This is the way to fix this:

sudo apt remove containerd 
sudo apt update
sudo apt install containerd.io -y
sudo rm /etc/containerd/config.toml

— — — — — — — — — — — — — — — — — — — — — — — — — —

As of 11 Jan 2023, Ubuntu 20 is broken for Kubernetes, because K8S 1.26 is not compatible with Containerd 1.5 (it needs 1.6). The workaround is to keep K8S from upgrading, and if it does, roll it back.

# apt remove — purge kubelet
# apt install -y kubeadm kubelet=1.25.5–00

You can determine what versions you are running with apt

# apt list containerd
containerd/focal-updates,focal-security,now 1.5.9–0ubuntu1~20.04.6 amd64 [installed]

# apt list kubelet
kubelet/kubernetes-xenial 1.26.0-00 amd64 [upgradable from: 1.25.5-00]

Links

• https://serverfault.com/questions/1118051/failed-to-run-kubelet-validate-service-connection-cri-v1-runtime-api-is-not-im
• https://kubernetes.io/blog/2022/11/18/upcoming-changes-in-kubernetes-1-26/#cri-api-removal
• https://serverfault.com/a/1118343
• https://www.reddit.com/r/kubernetes/comments/zhih71/hard_lesson_k8s_126_ubuntu_2204_containerd_159/