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Scenario #41
Cluster Management
K8s v1.21 to v1.22, custom CNI plugin
Cluster Upgrade Failing Due to CNI Compatibility
Cluster upgrade failed due to an incompatible version of the CNI plugin.
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What Happened
After upgrading the control plane, CNI plugins failed to work, resulting in no network connectivity between pods.
Diagnosis Steps
- 1Checked kubelet and container runtime logs – observed CNI errors.
- 2Verified CNI plugin version – it was incompatible with K8s v1.22.
Root Cause
CNI plugin was not upgraded alongside the Kubernetes control plane.
Fix/Workaround
• Upgraded the CNI plugin to the version compatible with K8s v1.22.
• Restarted affected pods and nodes.Lessons Learned
Always ensure compatibility between the Kubernetes version and CNI plugin.
How to Avoid
- 1Follow Kubernetes upgrade documentation and ensure CNI plugins are upgraded.
- 2Test in a staging environment before performing production upgrades.