diff --git a/content/en/docs/reference/setup-tools/kubeadm/kubeadm-upgrade.md b/content/en/docs/reference/setup-tools/kubeadm/kubeadm-upgrade.md
index 020e17d42a..da1d46de29 100644
--- a/content/en/docs/reference/setup-tools/kubeadm/kubeadm-upgrade.md
+++ b/content/en/docs/reference/setup-tools/kubeadm/kubeadm-upgrade.md
@@ -27,6 +27,13 @@ automatically renew the kubeadm managed certificates on this node, including tho
 To opt-out, it is possible to pass the flag `--certificate-renewal=false`. For more details about certificate
 renewal see the [certificate management documentation](docs/tasks/administer-cluster/kubeadm/kubeadm-certs).
 
+{{< note >}}
+The commands `kubeadm upgrade apply` and `kubeadm upgrade plan` have a legacy `--config`
+flag which makes it possible to reconfigure the cluster, while performing planning or upgrade of that particular
+control-plane node. Please be aware that the upgrade workflow was not designed for this scenario and there are
+reports of unexpected results.
+{{</ note >}}
+
 ## kubeadm upgrade plan {#cmd-upgrade-plan}
 {{< include "generated/kubeadm_upgrade_plan.md" >}}