macOS Catalina 10.15.6 seems to have introduced a bug that causes system crashes, especially when using virtualization software such as VirtualBox or VMware.
Users of virtualization software have reported that macOS 10.15.6 crashes repeatedly when running virtual machines.
A regression in the App Sandbox component of macOS 10.15.6 is reportedly leaking kernel memory, causing macOS to crash. The purpose of an App Sandbox is to provide protection to system resources and limit an app’s access to resources, such as memory.
VMware engineers have today diagnosed the issue and filed a “comprehensive” report with Apple, including a minimal reproduction case which should allow them to easily identify and address the issue. The engineer cautions that “it isn’t looking good” going forwards, and it will likely fall to Apple to resolve the issue in a software update to macOS. It is unclear if this issue exists in developer and public betas of macOS Big Sur.
The workaround suggested by many users and VMware engineers is to refrain from installing macOS 10.15.6, or shutting down virtual machines when they are not in use and rebooting the host as often as possible.