When adding the Hyper-V role on a VM (Windows 2012R2),  you get an error message saying “Hyper-V cannot be installed: A hypervisor is already running”.

The Solution

1 add the following 2 lines at the bottom of the .vmx file. (Stop the VM. Download the vmx file, edit it with notepad, upload it to the VM folder)

vhv.enable = “TRUE”
hypervisor.cpuid.v0 = “FALSE”

2 Enable the following setting for the VM

3 Enable Vmware virtual switch Security Promiscuous mode, otherwise the Hyper-v created Virtual machine will have no network connection.