grub2 broken after update

[Vitalii Rudiiko]

Hello!
My environment:
Windows Server 2016 Standart
Hyper-V: Сontainer Gen 2: Security Check EFI - Off

Distribution OS: ubuntu-18.04.3-live-server-amd64.iso
Distribution OS: xubuntu-18.04.3-desktop-amd64.iso

My experiments have shown that these packages are the cause of the breakdown:
grub-efi-amd64-signed amd64 1.93.16+2.02-2ubuntu8.15
grub-efi-amd64 amd64 2.02-2ubuntu8.15
grub-efi-amd64-bin amd64 2.02-2ubuntu8.15
grub2-common amd64 2.02-2ubuntu8.15
grub-common amd64 2.02-2ubuntu8.15

With package version 2.02-2ubuntu8.14, everything is fine.
grub-efi-amd64-signed (1.93.15+2.02-2ubuntu8.14)

What the breakdown leads to:
After the reboot, a black bootloader screen appears.

 GNU GRUB version 2.02
*Ubuntu
Advanced options for Ubuntu
System setup

Selecting any option returns back to the option selection.
Starting the kernel manually also returns to the selection of options.
A clean installation of the OS Ubuntu Server 18.04.3 amd64 during installation installs updates and leads to the same result.
A clean installation of the OS Xubuntu 18.04.3 works without an Internet connection, but after starting updates on the system itself, the result is the same.

Common bootloader recovery methods do not help.

[Sebastien Bacher (seb128)]

Thank you for your bug report. Do you have any error when upgrading grub?
One known regression from updates on bionic is
https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1868138

[Vitalii Rudiiko (vitalii-rudiiko)]

Hello!
No error.

On the OS xubuntu-18.04.3-desktop-amd64, I solved the problem.
After copying the old EFI to the outcrops of the GRUB, through a live disk.
In device /dev/sda1 EFI System
The operating system has worked as it should.

On the OS ubuntu-18.04.3-live-server-amd64, I have not tried it yet.

This Saturday I will report new data on this issue.

[Vitalii Rudiiko (vitalii-rudiiko)]

Hello!
I'll start with the most important thing.

Solution to the problem:
1. Boot through a live CD.
 I am using the xubuntu-18.04.3-desktop-amd64.iso

2. Open the terminal.
 sudo mount /dev/sda1 /mnt
 sudo rm /mnt/EFI/ubuntu/grubx64.efi
 sudo cp /cdrom/EFI/BOOT/grubx64.efi /mnt/EFI/ubuntu/
 sudo reboot

3. Press "Enter" the bootloader GRUB menu on *Ubuntu.
 The system starts to boot.

The cause of the problem:
After updating the bootloader GRUB (2.02-2ubuntu8.15), the file grubx64.efi changes.
The size of the broken file: 1116536 bytes.
Size of the working file from live CD: 1146744 bytes.
This file is on the /dev/sda1 (EFI System). Path EFI/ubuntu/grubx64.efi.

Recovery method tested on:
Distribution OS: ubuntu-18.04.3-live-server-amd64.iso
Distribution OS: ubuntu-18.04.4-live-server-amd64.iso
Distribution OS: xubuntu-18.04.3-desktop-amd64.iso