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Upgrade details#

Before you upgrade to MKE 4.2.0, review the changes detailed herein, as several require action be taken before the upgrade begins. The number of supported upgrade sources has been reduced restricted, cgroups v2 is now required on all nodes, and clusters carrying the legacy ingress-nginx addon go through an automated retirement flow. Several flags and restore behaviors have also changed in ways that may affect existing workflows.

Supported upgrade sources#

  • From MKE 3: only MKE 3.9.x is supported as an upgrade source for MKE 4.2.0. Upgrade to MKE 3.9.x first if you are on an earlier MKE 3 release.
  • From MKE 4: only MKE 4.1.3 or later is supported as an upgrade source for MKE 4.2.0. Clusters on 4.1.0 or 4.1.2 must first upgrade to 4.1.3 or later. Upgrading from 4.1.0 or 4.1.2 directly to 4.2.0 is blocked by the upgrade compatibility check.

cgroups v2 is required#

k0s 1.35 requires cgroups v2 on the host. Installs and upgrades now validate this requirement, and hosts that are still on cgroups v1 are rejected. Make sure all nodes are configured for cgroups v2 before you upgrade to MKE 4.2.0.

Removed flags and changed behavior#

  • The --force-ignore-etcd-v2-data flag has been removed. The etcd v2 data carried over from MKE 3 is now cleaned up, WAL and data, during migration, which also resolves a class of upgrade failures caused by newer etcd versions rejecting the v2 API.
  • The internal v2 flag has been removed.
  • The mkectl restore command now always bootstraps a single node and then joins the remaining nodes through the mkectl apply command. In-place restore has been removed.