Adding ESXi Host Directly to Cluster Prompts Maintenance Mode Warning

Products

• VMware vCenter Server

Issue/Introduction

When attempting to add a VMware vSphere ESXi host directly to a VMware vCenter Server (vCSA) cluster object, administrators receive the following warning message:

"Hosts will enter maintenance mode before they are moved to the cluster. You might need to either power off or migrate powered on and suspended virtual machines."

This behavior prevents administrators from adding the host to the cluster without potentially impacting running virtual machine workloads.

Environment

VMware vCenter Server 8.0U3
VMware vSphere ESXi 8.0U3

Resolution

To bypass the maintenance mode requirement and avoid impacting active workloads, perform the following workaround:

1. Add the ESXi host(s) to the vCenter inventory at the Datacenter level first, rather than adding them directly to the cluster object.

2. Once the host is successfully connected and exists in the vCenter inventory at the Datacenter level, move the host into the target cluster.

Moving an existing inventory host into the cluster allows it to inherit the cluster settings without being forced into maintenance mode.