When Resuming a suspended VM or reverting to a snapshot created in power-on or suspend states, Workstation Pro compares the CPU features with which the VM was created against the features actually available to the host environment running Workstation Pro.

If features requested during the VM creation are unavailable on the host environment, the VM resume operation fails. This ensures that a guest does not attempt to use unimplemented features. Because some CPU features are not supported in Host VBS Mode, attempting to resume suspended VMs or snapshots that were initially created on previous versions of Workstation Pro may fail.

For example, consider a physical PC that supports the RTM feature. A VM created with RTM enabled, will power on with RTM available to it, when Workstation Pro is running in traditional mode. However, the same VM running on the same PC will power on with RTM disabled, if Workstation Pro is in Host VBS Mode. This is because, as previously listed in the functional limitations list, Host VBS Mode does not support RTM.

Now consider a suspended VM which has a particular feature enabled is resumed some time later. If the particular feature is not available on the host environment of the resumed VM, the expected behavior is that the resume operation fails.
Note: The resume operation can fail on the same physical hardware, when the VM is suspended while operating in traditional mode and the resumed while in Host VBS Mode.
For example:
  1. Create a VM with RTM enabled.
  2. Start Workstation Pro with Hyper-V disabled and power on the VM on a physical hardware that supports RTM.
  3. Suspend the VM at some point after it is powered on.
  4. Enable Hyper-V. (The physical machine must be rebooted and Workstation Pro must be relaunched.)
  5. Resume the suspended VM.
  6. The resume operation fails.
Even though the physical hardware is the same, the resume operation fails because RTM is no longer supported in Host VBS Mode.
Note: If the VM is launched with Hyper-V enabled, the VM will not have the RTM capability, and so the suspended image created will also be RTM-free. Regardless of whether Hyper-V is disabled or left enabled, the resume VM operation will succeed.