Symptoms:
On iMac Pro or Mac Pro physical machine, when you install a macOS 10.15 virtual machine greater than macOS 10.15 Beta 5, or upgrade an existing macOS 10.15 virtual machine from an older version (10.15 Beta 5 or lower) to a newer version, you experience this symptom:

The macOS virtual machine panics during bootup process.

Note: This issue only happens on iMac Pro (model: iMacPro1,1) and Mac Pro (model: MacPro6,1) machines and does not happen on other Mac machine models.

VMware Fusion 11.x

This issue occurs because the macOS 10.15 virtual machine uses a multi-socket CPU configuration while running on a single-socket physical machine.

The crash can be avoided if the virtual CPU configuration of the virtual machine is changed from multi-socket configuration to single-socket configuration (all cores in one socket).

To resolve this issue, for existing macOS 10.15 virtual machine which already uses multi-socket CPU configuration, follow these steps to make it use single-socket configuration: 

Note: Starting with VMware Fusion 11.5, a new macOS 10.15 virtual machine is created with single-socket CPU configuration by default.

1. Power off the macOS virtual machine.
2. Right click the macOS virtual machine in Virtual Machine Library with Option key held down and select the "Open Config File in Editor" contextual menu.
3. Set "cpuid.coresPerSocket" to the same value as "numvcpus".