You booted the installer in bios mode and so were performing a bios mode install. If you want to install in EFI mode, then you need to boot the installer in EFI mode.
** Changed in: grub-installer (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1647861 Title: grub-install failed on raid install -- guessing I was supposed to have matching efi boot dirs on each hdd To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub-installer/+bug/1647861/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs