As far as I can see, the problem occurs only if the disk is MBR/MSDOS formatted and the installer is booted in the EFI mode. So we should create some test cases and test.
Test case 1: Prerequisites: - one disk; partition table -> GPT - no EFI-System-Partition - The installer is booted in EFI mode => [ -d /sys/firmware/efi ] && echo UEFI || echo BIOS Expected result: - Warning is printed about missing ESP, no crash Test case 2: Prerequisites: - one disk; partition table -> MBR/MSDOS - no EFI-System-Partition - The installer is booted in EFI mode => [ -d /sys/firmware/efi ] && echo UEFI || echo BIOS Expected result: - Warning is printed about missing ESP, no crash Test case 3: Prerequisites: - one disk; partition table -> GPT - EFI-System-Partition exists - The installer is booted in EFI mode Expected result: - Installation succeeds Test case 4: Prerequisites: - one disk; partition table -> MBR/MSDOS - EFI-System-Partition exists - The installer is booted in EFI mode Expected result: - Installation succeeds In my opinion, it is a bug in ubiquity, that it is not complaining about a missing ESP before the installation begins. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1767703 Title: Calling 'apt-install grub-efi-amd64-signed' failed To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub-installer/+bug/1767703/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs