grub2 install fail

[Marco Antonio Molinari]

ubuntu@ubuntu:~$ lsb_release -rd
Description: Ubuntu 18.04 LTS
Release: 18.04

ubuntu@ubuntu:~$ apt-cache policy grub2-common
grub2-common:
  Installed: 2.02-2ubuntu8
  Candidate: 2.02-2ubuntu8.2
  Version table:
     2.02-2ubuntu8.2 500
        500 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
 *** 2.02-2ubuntu8 500
        500 http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages
        100 /var/lib/dpkg/status

fail install grub at end installation

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubiquity 18.04.14 [modified: lib/partman/automatically_partition/question]
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: Thu Aug 9 16:10:49 2018
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed boot=casper quiet splash ---
LiveMediaBuild: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)