Rollback from k8s 1.27.1 to 1.26.3 fails

General Discussions microk8s
1

Hi we have k8s 1.27.1 with coredns compatible version 1.10.0 and k8s 1.26.3 with compatible version of 1.9.3.
When we upgrade our cluster 1.26.3 => 1.27.1 it was fine. When we rollback from 1.27.1 => 1.26.3 we have below fatal error from kubeadm. Any pointers? Is this a k8s issue? It is referring somewhere to 1.10.0 though kubeadm config file is updated to use 1.9.3 during upgrade(rollback) plan/init/upgrade phase.

    "[upgrade/postupgrade] FATAL post-upgrade error: unable to get list of changes to the configuration.: start version '1.10.0' not supported",
2

Anyone has any inputs here please?

3

Hi Kiran,
It seems delete coredns deployment might be an workaround.
$kubectl delete deployment -n kube-system coredns
After that " /usr/local/bin/kubeadm upgrade apply" will be completed. the coredns deployment should be back after kubeadm upgrade .