"The virtual machine has virtual disk in linked-clone mode" error when enabling vSphere Fault Tolerance (FT) on a virtual machine

Products

• VMware vSphere ESXi

Issue/Introduction

• When trying to enable Fault Tolerance (FT) on a virtual machine, the task fails with the message: 

The Fault Tolerance configuration of the entity VM_Name has an issue: "The virtual machine has virtual disk in linked-clone mode".
The operation is not supported on the object.
The Fault Tolerance configuration of the entity has an issue: "The virtual machine has one or more snapshots or disks that need consolidation that make it incompatible for vSphere Fault Tolerance protection".

Cause

• The VM contains active snapshots, placing the virtual disks in a linked-clone state.
• Legacy and standard FT implementations do not support enabling protection on Virtual Machines that currently have existing snapshots or are running on delta disks (linked-clones).

Resolution

No snapshots should be present on the Virtual Machine when configuring Fault Tolerance.

To resolve the issue:

1. Delete all the snapshots for the Virtual Machine.
2. Enable Fault Tolerance.