**How can I mitigate this prior to installing 1.5.5?**

1. Export existing PodSecurityPolicy objects:
  * `kubectl get podsecuritypolicies -o yaml > psp.yaml`
2. Review and delete any PodSecurityPolicy objects you do not want all pod-creating users to be able to use (NOTE: Privileged users that were making use of those policies will also lose access to those policies). For example:
  * `kubectl delete podsecuritypolicies/my-privileged-policy`

version kubectl's rolling-update command is compatible with Kubernetes 1.4 and higher only if you specify a new replication controller name. You will need to update to kubectl 1.4 or higher to use the rolling update command against a 1.4 cluster if you want to keep the original name, or you'll have to do two rolling updates.

If you do happen to use old version kubectl's rolling update against a 1.4 cluster, it will fail, usually with an error message that will direct you here. If you saw that...