I am on a T2 Mac and am trying to install the macOS Big Sur beta onto an external drive, but I’m running into issues. Is there an official guide for this? Step 1: I downloaded the Install Profile and successfully downloaded the installer to my Catalina Mac. Step 2: I configured a 12GB HFS+ partition on an external drive and used the createinstallmedia utility from inside the beta installer package to create a bootable install media volume. Step3: I also have an APFS external volume ready to be the installation target media for Big Sur. Step 4: I rebooted my Mac and held Option to select the bootable install drive. The computer starts to boot but complains that « A software upgrade is required to use this startup disk. You can update now or select another startup disk » Note: I did reboot my Mac with Cmd-R and ran the Startup Security Utility to allow booting from external media, and even tried setting Secure Boot to « Medium Security » and « No Security ». Nothing works, I am getting the same message. Is there anything that I’m doing wrong? I’d love a support article on this.