Adding virtual machines to a protection group fails with an error if you did not map the devices of the virtual machine.

Problem

When you add a virtual machine to a protection group, you see the error Unable to protect VM 'virtual machine name' due to unresolved devices.

Cause

You did not map the devices of the virtual machine on the protected site to the corresponding devices on the recovery site.

Solution

Configure the protection settings of the virtual machine as described in Modifying the Settings of a Virtual Machine in an Array-Based, Virtual Volumes, or vSphere Replication Protection Group.