I made live-usb for 16.04.3 LTS from within UBUNTU 16.04.2 (updated). I disconnected all the other HD's except one and installed the newly created LIVE USB Ubuntu 16.04.3 LTS over the only remaining hard disk with linux MINT. At some point of the installation the system says cannot install boot loader (GRUB) on HD!

[Bernard Catalan]

1.) I created a USB Live Installer for Ubuntu LTS 16.04.3 from within Ubuntu 16.04.2 LTS (updated reg.), using ubuntu live USB creator.
2.) I disconnected all other 2 HD's on my computer then installed the newly created Live USB Ubuntu 16.04.3 LTS on the remaining HD with existing Linux Mint (latest stable).
    I used the 2nd option of reusing the existing partitions used by Linux Mint. (can't recall if I reformatted, but I recall selecting the "mount partion as root" anew (ext4).
3.) Sometime later during the installation, system says cannot write boot loader on HD and system will no be able to boot.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubiquity 2.21.63.4 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 4.10.0-28.32~16.04.2-generic 4.10.17
Uname: Linux 4.10.0-28-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.10
Architecture: amd64
CasperVersion: 1.376.2
Date: Thu Oct 19 12:14:26 2017
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/ubuntu.seed boot=casper only-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu 16.04.3 LTS "Xenial Xerus" - Release amd64 (20170801)
ProcEnviron:
 LANGUAGE=en_PH.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_PH.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Phillip Susi (psusi)]

Your disk is currently partitioned to boot in bios mode, but you booted the installer in EFI mode. A warning message prompted you that this could be a problem and recommended performing a bios mode install instead, but you chose not to. You either need to perform the bios mode install, or partition the disk using GPT and set up an EFI system partition to install in EFI mode. This will be done for you if you choose the "use entire disk" guided install option.