I got this problem when install Ubuntu too. My laptop have NVIDIA graphic card and secure boot disabled. The installer see the error but when I remove and reboot laptop, Ubuntu installed on laptop but missing NVIDIA XServer Settings. But funny thing that it's appear on my Ubuntu boot media that using 20.04.1 version but giving no error in last time. So maybe the NVIDIA package from internet have problem (I'm not specialize in Linux but still know something about computer). Maybe this information can help.
I got this problem when install Ubuntu too. My laptop have NVIDIA graphic card and secure boot disabled. The installer see the error but when I remove and reboot laptop, Ubuntu installed on laptop but missing NVIDIA XServer Settings. But funny thing that it's appear on my Ubuntu boot media that using 20.04.1 version but giving no error in last time. So maybe the NVIDIA package from internet have problem (I'm not specialize in Linux but still know something about computer). Maybe this information can help.