Anthos GKE - March 20th, 2026 [Change]

## Change Change **Important: Mandatory flag for admin cluster upgrades** If an update or upgrade to advanced admin clusters fails in versions 1.32 and newer, don't delete the external bootstrap cluster from the workstation. The bootstrap cluster contains required information about states that you need to resume the update or upgrade. If an update or upgrade to admin clusters fails, and you re-run `gkectl upgrade admin`, you must add the flag `--reuse-bootstrap-cluster` or you can lose critical data.