Parallels has issued a “critical and urgent Windows 8 service advisory” recommending that users not perform an upgrade to Windows 8 form an existing Windows install. Doing so at this time can do damage to the virtual machine and cause data loss.
The short release does not address the specific failure of an in-place upgrade. The Parallels advisory says “We’re working hard on completing our testing of the Windows 8 upgrade, and will inform you via in-product notification when you can successfully upgrade to Windows 8.” Updates on the status of the Parallels revision can be found on the support pages for the application.
A full installation of Windows 8 without migrating any applications or data “should work just fine” on the latest build of Parallels Desktop according to the service advisory.
