Kubernetes Upgrade Checklist: The Runbook I Wish I Had

Kubernetes Upgrade Checklist (Minor Version): the runbook I wish I had Last Updated: 2025-12-28 Quick Navigation - [Methodology](#methodology) I've watched "small" Kubernetes minor upgrades take down perfectly healthy apps. It usually starts with one removed API, one too-old CNI, or one webhook nobody owns anymore. Our Methodology This guide is based on official Kubernetes documentation and release notes, analysis of relevant GitHub commits, hands-on community testing and incident postmortems, vendor compatibility matrices for CNIs/CSIs, and the author's real-world upgrade experience. We cross-checked behaviors in both kubeadm and managed-service workflows to highlight common failure modes and reliable mitigations. What a minor upgrade really changes Minor upgrades change the middle number in x.y.z (for example, 1.33 to 1.34). This is where Kubernetes removes APIs, shifts defaults, and tightens compatibility rules, so treat it like a compatibility audit, not a version bump. - **Do not