installer fails when installing grub2

[ajpro]

after the tedious installation & downloading, on the final stage the installation fails when trying to install grub2

ProblemType: Bug
DistroRelease: Ubuntu 16.10
Package: ubiquity 16.10.14
ProcVersionSignature: Ubuntu 4.8.0-22.24-generic 4.8.0
Uname: Linux 4.8.0-22-generic x86_64
ApportVersion: 2.20.3-0ubuntu8
Architecture: amd64
CasperVersion: 1.379
Date: Wed Apr 5 23:59:25 2017
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/lubuntu.seed boot=casper only-ubiquity quiet splash ---
LiveMediaBuild: Lubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.1)
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)