Cannot install grub2

[kapil.v]

Cannot complete installation of lubuntu to disk. Says unable to install boot loader.
Retried with Internet connection, still no chance.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubiquity 18.04.14
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CasperVersion: 1.394
Date: Fri Jun 15 06:56:04 2018
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/lubuntu.seed boot=casper only-ubiquity quiet splash ---
LiveMediaBuild: Lubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
ProcEnviron:
 LANGUAGE=en_IN
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_IN
 LC_NUMERIC=C.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Phillip Susi (psusi)]

Your disk is currently partitioned to boot in bios mode, but you booted the installer in EFI mode. You either need to boot the installer in bios mode, 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.