System Extensions in Big Sur

Summary: Don't install Big Sur until you make sure your USB/Serial connection will work!

Warnings for Legacy System Extensions started to appear on reboot after installing macOS 10.15.4

These extensions are provided by the manufacturers (FTDI, Silicon Labs etc.) of internal and external USB/Serial adapters (UARTS) and are needed  for CAT control of all serial port (non-LAN) based radios, rotor controllers, etc.

Apple intends to eventually prohibit kernel extensions for security reasons and replace the functionality with DriverKit extensions running in user space.

The UART manufacturers have announced their intention to support Apple's migration from Kernel Extensions to DriverKit Extensions.

Many UARTs are already supported automatically by Apple supplied Driver Kit extensions in the Big Sur beta.

As Apple System Extensions and DriverKit adds functionality, kernel extensions with matching functionality will not load.

Native DriverKit Support:

Current Status October 1, 2020 macOS Version 11.0 Beta 9 (20A5384c). Updated as more information becomes available.

If you are not sure that your device will be supported please do not upgrade your Mac to Big Sur without being able to fall back to your current version of macOS.

The Big Sur beta DriverKit currently supports the following devices without the end user having to install any driver:

The Big Sur beta does not currently support the following devices


Tested here with Yaesu FT-991.

This may not be possible when Big Sur is officially released.