Select Boot Maintenance Manager and click.
You'll be brought into an EFI text-mode GUI. I was able to fix the UEFI problems as follows (credit to VirtualBox forum):
After manually directing EFI to boot into macOS for the first time, macOS automatically fixed-up the boot partition, and subsequent boots worked properly. In my case, after installing macOS into a Virtual Machine according to these instructions (running macOS installer from an ISO downloaded from Apple), on first boot, the boot partition was present but unconfigured (probably no boot image installed). By now you may have surmised boot.efi is an EFI standard filename that lives at an EFI standard path in a disk partition, and it contains os-specific boot firmware (e.g. Ultimately, the objective is provide a boot partition that contains macOS boot.efi. Your immediate objective is to help EFI locate and execute os-specific boot firmware. However, assuming you have a macOS recovery partition on that disk, it should contain a copy of boot.efi (macOS-specific boot firmware) that you can boot into the OS with. UEFI requires intervention because EFI firmware on the Mac's motherboard cant find valid OS-specific EFI boot firmware in the standard location on disk.
