The VM has RDM attached to a BusLogic SCSI controller.
The VM has a SATA disk attached - Zerto Virtual Replication does not support replicating VMs with SATA disks in vSphere. SATA CD devices are compatible.
NiCs attached to the VM with an identical MAC address.
In a Hyper-V environment:
VMs that are part of Hyper-V Replica. This feature creates duplicates of VMs which are problematic for Zerto to track. In order to disable Hyper-V Replica for VMs you wish to protect, please right click them and select 'Remove replication'.
VMs that have pass-through disks attached to them. This is similar to RDM in VC. However, Zerto does not support replication of such disks.
VMs with shared VHDX disks.
If none of the options above is the case here, please contact Zerto support and provide the following information:
Screenshot of the VM tab (click on the VM in vSphere client, then on Zerto tab).
VRA tab screenshot.
Zerto alerts and events csv files.
The VM settings (VM properties screenshot / VMX file / MOB screenshot).