While cloning a Virtual Machine, the following error may occur when the cloning process is at 90%:
Clone virtual machine
Number of virtual devices exceeds the maximum for a given controller.
Reconfiguring the new Virtual Machine
When this is the case, you probably have selected the “Edit Virtual hardware (Experimental)” checkbox during the Cloning wizard.
As long as this issue hasn’t been fixed, the only advice is to clone the machine, and then edit the virtual hardware, before you turn on the machine for the first time.