synchronus exception 333ae89c

[mdidomenico4]

i'm attempting to get an rpi3 running with rocky v9. i managed to download the minimal iso and burn it to a usb attached sata disk. i also downloaded the uefi firmware v1.39 and flashed that to the sd card. i'm able to get to the uefi bios screens, but when i try to boot the usb sata disk, it stops immediately with the sychronus exception 333ae89c

does anyone know what specifically might have gone wrong or the best method for troubleshooting it?