vMotion compatibility check displays a warning "The operation is not allowed in the current state of the host." during migration to a DRS cluster, when one or more cluster nodes are in maintenance mode

Products

• VMware vCenter Server

Issue/Introduction

• You attempt to manually migrate a virtual machine using vSphere Client
• in the migration wizard under '2 Select a compute resource' you select the option 'Clusters' 
• As target you select a DRS cluster, where one or more of the cluster members are in maintenance mode, upon which the 'Compatibility' window on below the the selection list shows a warning message:

The operation is not allowed in the current state of the host

similar to the following example:

Environment

VMware vCenter Server 7.0.x

VMware vCenter Server 8.0.x

Cause

When you select a cluster as migration target, the distributed resource scheduler (DRS) will run compatibility checks against all cluster members in order to verify where it will be able to place the VM, no matter which mode or state the host is currently in.

If DRS finds that there are any hosts where the VM cannot be placed on due to the state their are currently in, aka when the host is in maintenance-, quarantine- or standby mode, or disconnected from vCenter Server, DRS will report the above message in the wizard for transparency reasons, to inform the user which of the cluster members it will not be able to use. 

Resolution

This is an expected behavior.

The message shown in the migration wizard is meant as an information related to where DRS will be able to place the virtual machine and where it won't. 

This will not prevent you from moving on and finishes the migration, but it allows you to use the information and act upon it.