KubeVersionMismatch #

Meaning #

Different semantic versions of Kubernetes components running. Usually happens during kubernetes cluster upgrade process.

Full context

Kubernetes control plane nodes or worker nodes use different versions. This usually happens when kubernetes cluster is upgraded between minor and major version.

Impact #

Incompatible API versions between kubernetes components may have very broad range of issues, influencing single containers, through app stability, ending at whole cluster stability.

Diagnosis #

Check existing kubernetes versions via kubectl get nodes and see VERSION column
Check if there is ongoing kubernetes upgrade - especially in managed services in the cloud

Mitigation #

Drain affected nodes, then upgrade or replace them with newer ones, see Safely drain node
Ensure to set proper control plane version and node pool versions when creating clusters.
Ensure auto cluster updates for control plane and node pools.
Set proper maintenance windows for the clusters.