Kubeadm marks the master node only at the initial setup after that during the package upgrade procedures sometimes the role goes away and we are left with a cluster which has a missing master role. To fix this situation edit the node that supposed to be the master:
“kubectl edit node NODE”
and add
”
labels:
node-role.kubernetes.io/master: “”
spec:
taints:
– effect: NoSchedule
key: node-role.kubernetes.io/master
timeAdded: null
”