"The unattend answer file contains an invalid product key. Either remove the invalid key or provide a valid product key in the unattend answer file to proceed with Windows installation."
This happens because the configuration of your Windows virtual machine includes a floppy disk drive that is connected to the Unattended.fdd file.
Resolution
1. Open the configuration of your virtual machine by choosing Virtual Machine > Configure from the menu. If you are working inCoherence or Full Screen, you need to switch to another view mode to be able to access the menu.
2. Click the Hardware tab and select Floppy Disk.
3. Disconnect the floppy disk by clearing the Connected option, and click OK to save your settings.
Once the floppy disk is disconnected, start the upgrade again.