ERROR: Unable to add the virtual machine in %1

Symptoms

You get the following message when trying to convert your virtual machine:

Unable to add the virtual machine in %1.
 

Cause

The above error appears when Parallels Desktop is unable to convert a virtual machine to the new version because there are snapshots in that virtual machine.

Resolution

1. Try installing the previous version of Parallels Desktop:
- Re-install Parallels Desktop using your old DMG installation file or the installation CD/DVD.

2. Launch your virtual machine using the newly installed version of Parallels Desktop.

3. Open Snapshots Manager (go to Virtual machine > Manage Snapshots...).

4. Delete all the snapshots.