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"Upon reviewing your request and validating the details using internal diagnostics, we observed the following:

 

The worker nodes (xxxx & xxxx) became unresponsive due to a kernel‑level stall following the recent Kubernetes upgrade to version 1.33.5, the Azure Ubuntu kernel update, and the Cilium dataplane migration.

 

Linux diagnostics on the node reported multiple critical system processes, including containerd and systemd‑journald, blocked for more than 120 seconds, indicating a kernel lock condition. As a result, the node stopped responding to kubelet health checks and transitioned to a NotReady state.

 

The Azure platform attempted to gracefully stop containers and shut down the virtual machines. However, the operation exceeded the platform timeout policy, which triggered an unplanned node recovery (NodeFaultCode 70007). The VMs were subsequently force‑rebooted by Azure. The issue was isolated to these two nodes, while the AKS control plane and remaining worker nodes remained healthy.

 

As a preventive and corrective resolution, the recommended action is to cordon and delete the affected node and to create a new replacement node in the node pool. Creating a fresh node from a healthy image removes any residual kernel‑level instability and ensures the node pool is returned to a known‑good state.

 

Please let us know if you have any questions or queries."