[Bug 1575092] Re: Reinstall of Ubuntu 16.04 over failed upgrade of Ubuntu (15.10 -> 16.04) results in grub installation failure

[Robert B]

Thanks for this explanation. I re-installed 16.04 from scratch, erasing
the disk. Not without difficulties, though, as I got an error message
about not being able "to mount a file system with type vfat in SCSI1"
(fixed that by booting from USB into a live system and writing a new GPT
partition table before re-attempting installation onto the now empty
disk with empty partition table).

The new installation was done in UEFI mode.

A note about the warning message that you referred to, i.e.:

"This machine's firmware has started the installer in UEFI mode but it
looks like there may be existing operating systems already installed
using "BIOS compatibility mode". If you continue to install Debian in
UEFI mode, it might be difficult to reboot the machine into any BIOS-
mode operating systems later.

If you wish to install in UEFI mode and don't care about keeping the
ability to boot one of the existing systems, you have the option to
force that here. If you wish to keep the option to boot an existing
operating system, you should choose NOT to force UEFI installation
here."

On re-reading this message in light of what you explained it now makes
sense. At the moment, however, I didn't realise that "one of the
existing systems" actually included the one I was trying to repair
(which was the only system installed). Somehow I thought the message
referred to Windows or other systems.

The dialogue box then provides two options: "Go Back " and "Continue in
UEFI mode".

What I was missing to see was an option to "Continue in BIOS mode". Am I
right in guessing that that needs to be selected in the BIOS before
rebooting the machine?

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https://bugs.launchpad.net/bugs/1575092

Title:
  Reinstall of Ubuntu 16.04 over failed upgrade of Ubuntu (15.10 ->
  16.04) results in grub installation failure

Status in grub-installer package in Ubuntu:
  Invalid

Bug description:
  I had a working Ubuntu 15.10 installation (which itself was an upgrade
  from an earlier release). Got prompted if I wanted to upgrade to 16.04
  and answered yes. During the upgrade several dozen packages failed to
  install, many of them libraries. I was eventually left with a system
  that would not work so I decided to reinstall the OS, keeping existing
  user files intact (booting from USB). The install proceeded without
  problems but at the end I got the error message "The 'grub-efi-
  amd64-signed' package failed to install into / target/." Now I'm left
  with a computer without any working OS.

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: ubiquity 2.21.63
  ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
  Uname: Linux 4.4.0-21-generic x86_64
  ApportVersion: 2.20.1-0ubuntu2
  Architecture: amd64
  CasperVersion: 1.376
  Date: Tue Apr 26 17:51:26 2016
  InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/ubuntu.seed boot=casper only-ubiquity quiet splash --- cdrom-detect/try-usb=true noprompt
  LiveMediaBuild: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
  ProcEnviron:
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
  SourcePackage: grub-installer
  UpgradeStatus: No upgrade log present (probably fresh install)

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