Actually, I just shift to an older version of lubuntu, 16 if I'm correct.
It worked perfectly. Thanks for your help everyone.

Le mardi 8 mai 2018, Tommi <email address hidden> a écrit :

> I can confirm, that it affected my system as well (see
> https://bugs.launchpad.net/ubuntu/+source/grub-installer/+bug/1769732)
> trying to install on a non-UEFI system.
> BIOS settings for USB-Boot were set to UEFI-Boot, though.
>
> I changed the settings in BIOS, no need to change anything on the
> installer (media). The install wizard detects the drives correctly. I
> still needed to set the mounting pount of sdc (where Ubuntu was to be
> installed) as well as (important!) the bootloader set to sda.
>
> --
> You received this bug notification because you are subscribed to a
> duplicate bug report (1768404).
> https://bugs.launchpad.net/bugs/1767703
>
> Title:
>   Calling 'apt-install grub-efi-amd64-signed' failed
>
> Status in grub-installer package in Ubuntu:
>   Confirmed
>
> Bug description:
>   /plugininstall.py: Exception during installation:
>   /plugininstall.py: Traceback (most recent call last):
>   /plugininstall.py:   File "/usr/share/ubiquity/plugininstall.py", line
> 1739, in <module>
>   /plugininstall.py:     install.run()
>   /plugininstall.py:   File "/usr/share/ubiquity/plugininstall.py", line
> 61, in wrapper
>   /plugininstall.py:     func(self)
>   /plugininstall.py:   File "/usr/share/ubiquity/plugininstall.py", line
> 227, in run
>   /plugininstall.py:     self.configure_bootloader()
>   /plugininstall.py:   File "/usr/share/ubiquity/plugininstall.py", line
> 971, in configure_bootloader
>   /plugininstall.py:     "GrubInstaller failed with code %d" % ret)
>   /plugininstall.py: ubiquity.install_misc.InstallStepError:
> GrubInstaller failed with code 1
>
>   ************************
>
>   +++++++++++++++++++++++++++++++++++++++++++++
>   MBR-EFI-GPT explanations/requirements:
>
>   https://askubuntu.com/questions/500359/efi-boot-partition-and-biosgrub-
> partition
>   https://askubuntu.com/questions/831216/how-can-i-
> reinstall-grub-to-the-efi-partition
>   https://askubuntu.com/questions/578928/why-i-need-
> several-boot-partitions-efi-and-bios-grub
>   +++++++++++++++++++++++++++++++++++++++++++++
>
>
>   Manual fix: https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/
> 1766945/comments/3
>
>   also see: https://bugs.launchpad.net/ubuntu/+source/grub-
>   installer/+bug/1763441/comments/2
>
>   https://help.ubuntu.com/community/Boot-Repair
>
>   ************************
>
>   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
>   CurrentDesktop: ubuntu:GNOME
>   Date: Sat Apr 28 20:39:35 2018
>   InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed
> boot=casper only-ubiquity quiet splash ---
>   LiveMediaBuild: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64
> (20180426)
>   ProcEnviron:
>    LANGUAGE=de_DE.UTF-8
>    PATH=(custom, no user)
>    XDG_RUNTIME_DIR=<set>
>    LANG=de_DE.UTF-8
>    LC_NUMERIC=C.UTF-8
>   SourcePackage: grub-installer
>   UpgradeStatus: No upgrade log present (probably fresh install)
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ubuntu/+source/grub-installer/
> +bug/1767703/+subscriptions
>


-- 
RAZAFITSIAROVANA Harimbola