Comment 2 for bug 1868228

The error in your dpkg log is:

Setting up grub-efi-amd64-signed (1.128.2+2.04-1ubuntu12.2) ...
Installation pour la plate-forme x86_64-efi.
grub-install : attention : Cannot set EFI variable Boot0000.
grub-install : attention : efivarfs_set_variable: writing to fd 7 failed: Argument invalide.
grub-install : attention : _efi_set_variable_mode: ops->set_variable() failed: Argument invalide.
grub-install : erreur : failed to register the EFI boot entry: Argument invalide.
dpkg: error processing package grub-efi-amd64-signed (--configure):
 installed grub-efi-amd64-signed package post-installation script subprocess returned error exit status 1

Unfortunately this indicates there was a problem with grub trying to talk to your UEFI firmware in order to register Ubuntu as a boot option.

Please attach the output of the command 'sudo efibootmgr -v'.