## Before Upgrading

* If you need to downgrade from 1.10 to 1.9.x, downgrade to v1.9.6 to ensure PV and PVC objects can be deleted properly.

* Fix GCE etcd scripts to pass in all required parameters for the etcd migration utility to correctly perform HA upgrades and downgrades ([#61956](https://github.com/kubernetes/kubernetes/pull/61956), [@jpbetz](https://github.com/jpbetz))

* Fix GCE etcd scripts to pass in all required parameters for the etcd migration utility to correctly perform HA upgrades and downgrades ([#61957](https://github.com/kubernetes/kubernetes/pull/61957), [@jpbetz](https://github.com/jpbetz))

				allErrs = append(allErrs, field.Invalid(field.NewPath("spec", "clusterIPs").Index(i), service.Spec.ClusterIPs, "may not change once set"))
			}
		}

	// something has been released (downgraded)
	case len(oldService.Spec.ClusterIPs) > len(service.Spec.ClusterIPs):
		// primary ClusterIP has been released
		if len(service.Spec.ClusterIPs) == 0 {

  This feature will not be fully enabled until a future Kubernetes release (likely to be v1.29), but is added in v1.28 to enable
  safe rollback on downgrade. ([#118339](https://github.com/kubernetes/kubernetes/pull/118339), [@jpbetz](https://github.com/jpbetz)) [SIG API Machinery, Auth, Cloud Provider and Testing]

		newService:         makeServiceWithClusterIp("10.0.0.10", []string{"10.0.0.10", "2000::1"}),
		expectedClusterIP:  "10.0.0.10",
		expectedClusterIPs: []string{"10.0.0.10", "2000::1"},
	}, {
		name:               "update - downgrade",
		oldService:         makeServiceWithClusterIp("10.0.0.10", []string{"10.0.0.10", "2000::1"}),
		newService:         makeServiceWithClusterIp("10.0.0.10", []string{"10.0.0.10"}),
		expectedClusterIP:  "10.0.0.10",

- fluentd-elasticsearch is unchanged from 1.10: v2.0.4 ([#58525](https://github.com/kubernetes/kubernetes/pull/58525))
- The fluent-plugin-kubernetes_metadata_filter plugin in fluentd-elasticsearch has been downgraded to version 2.0.0 ([#67544](https://github.com/kubernetes/kubernetes/pull/67544))
- fluentd-gcp is unchanged from 1.10: v3.0.0. ([#60722](https://github.com/kubernetes/kubernetes/pull/60722))

    * To downgrade the cluster to version that does not support scale-to-zero feature:
    * 1. make sure there are no hpa objects with minReplicas=0. Here is a oneliner to update it to 1:

- [`KT-61078`](https://youtrack.jetbrains.com/issue/KT-61078) K2: Compilation fails in FirSerializer trying to serialize nested class
- [`KT-66372`](https://youtrack.jetbrains.com/issue/KT-66372) KMP: JVM dependency can be downgraded by metadata dependency
- [`KT-66431`](https://youtrack.jetbrains.com/issue/KT-66431) KMP: External Target Compilation friendArtifactResolver throws ClassCastException

- Support a smooth upgrade from client-side apply to server-side apply without conflicts, as well as support the corresponding downgrade. ([#90187](https://github.com/kubernetes/kubernetes/pull/90187), [@julianvmodesto](https://github.com/julianvmodesto)) [SIG API Machinery and Testing]