Bug#1033678: installation-reports: Unbootable install: MBR partition unusable with UEFI

[Pascal Hambourg <pascal@plouf.fr.eu.org>]

Hello,

On 30/03/2023 at 01:21, Dima Kogan wrote:
> I'm installing from a USB drive. To make this work, I had to turn off
> secure-boot and UEFI in the BIOS.

Why ? What happens if UEFI boot is enabled ?
How did you prepare the USB drive ?
What installation image did you use (full file name and URL please) ?

> Some
> searching tells me this is because GPT partitions are required for UEFI
> booting

There is no such requirement in the UEFI specification. UEFI boot 
supports either GPT or MSDOS.

> I'm not 100% sure of the exact cause. But I suspect strongly is that
> booting the install media without UEFI broke installing to an UEFI-only
> disk.

If the installer was booted in BIOS/legacy mode, it installed GRUB for 
legacy boot.