Cloning operation fails, error message states that host is in invalid state.

Running: VMware ESXi 6.0

When I try to clone a VM, I get the following:

Traceback (most recent call last):
  File "./clone_vm.py", line 397, in <module>
    main()
  File "./clone_vm.py", line 372, in main
    args.resource_pool, False)
  File "./clone_vm.py", line 252, in clone_vm
    WaitForTask(task)
  File "/usr/lib/python2.6/site-packages/pyvmomi-6.5.0.2017.5_1-py2.6.egg/pyVim/task.py", line 139, in WaitForTask
    raise task.info.error
pyVmomi.VmomiSupport.InvalidHostState: (vim.fault.InvalidHostState) {
   dynamicType = <unset>,
   dynamicProperty = (vmodl.DynamicProperty) [],
   msg = 'The operation is not allowed in the current state of the host.',
   faultCause = <unset>,
   faultMessage = (vmodl.LocalizableMessage) [],
   host = 'vim.HostSystem:host-38'
}

I have checked the host system to ensure that it is not in standby mode or in maintenance mode. Everything looks good on the web client.

Any ideas of what could be causing this?