Kernel Panic- not syncing: VFS: Unable to mount root fs on unknown block (0,0)

Question

my laptop went in to the hibernation during distro upgrade . I run in to this error during boot :

Kernel Panic- not syncing: VFS: Unable to mount root fs on unknown block (0,0)

Here the screenshot with the error details: https://i.stack.imgur.com/ALcIh.jpg To fix it I did steps from this topic: kernel panic not syncing vfs unable to mount root fs on unknown block oo swapper not tainted Here all steps I did :

ubuntu@ubuntu:~$ sudo mount /dev/mapper/ubuntu--vg-root /mnt
ubuntu@ubuntu:~$ sudo mount --bind /dev /mnt/dev
ubuntu@ubuntu:~$ sudo mount --bind /dev/pts /mnt/dev/pts/
ubuntu@ubuntu:~$ sudo mount --bind /proc/ /mnt/proc/
ubuntu@ubuntu:~$ sudo mount --bind /sys/ /mnt/sys/
ubuntu@ubuntu:~$ sudo mount --bind /run /mnt/run
ubuntu@ubuntu:~$ sudo chroot /mnt
root@ubuntu:/# uname -a
Linux ubuntu 5.4.0-26-generic #30-Ubuntu SMP Mon Apr 20 16:58:30 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
root@ubuntu:/# cal /boot/
config-5.4.0-26-generic      System.map-5.4.0-26-generic
initrd.img-5.4.0-26-generic  
root@ubuntu:/# update-initramfs -u -k 5.4.0-26-generic
update-initramfs: Generating /boot/initrd.img-5.4.0-26-generic
root@ubuntu:/# update-grub2
Sourcing file `/etc/default/grub'
Sourcing file `/etc/default/grub.d/init-select.cfg'
/usr/sbin/grub-mkconfig: 275: cannot create /boot/grub/grub.cfg.new: Directory nonexistent

The last command had an Issue .

Here additional Info :

root@ubuntu:/# grub-install -v
grub-install: Info: executing modprobe efivars 2>/dev/null.
grub-install: Info: Looking for /sys/firmware/efi ...
grub-install: Info: ...found.
x86_64-efi wird für Ihre Plattform installiert.
grub-install: Info: »/boot/grub/device.map« kann nicht geöffnet werden: Datei oder Verzeichnis nicht gefunden.
grub-install: Fehler: EFI-Verzeichnis kann nicht gefunden werden.

Can any one please help me with this ? Thank you !

[EDIT] I did all steps again with mounting boot partition . The only change I had was here :

update-initramfs -u -k 5.4.0-26-generic
ln: Die harte Verknüpfung '/boot/initrd.img-5.4.0-26-generic.dpkg-bak' => '/boot/initrd.img-5.4.0-26-generic' konnte nicht angelegt werden: Vorgang nicht zulässig
update-initramfs: Generating /boot/initrd.img-5.4.0-26-generic

Any one any Idea ?

Here some additional Info :

lsblk -f
sda                                                                           
├─sda1
│    vfat   FAT32       18E8-5B11                               465,6M     9% /boot
├─sda2
│    ext2   1.0         6c5d8821-3ae5-4dc7-9b50-4b1eedbd6ec5                  
└─sda3
     LVM2_m LVM2        durg23-i4ZY-vzY0-2BQU-IoGz-j4cU-JCVgvQ                
  ├─ubuntu--vg-root
  │  ext4   1.0         346cd866-61d7-4339-bd6f-043897a89b2a        7G    93% /
  └─ubuntu--vg-swap_1
     swap   1           387b8baf-13e0-4be6-8c60-659f9aa7a4b4                  
sdb  iso966 Jolie Ubuntu 20.04 LTS amd64
│                       2020-04-23-07-51-42-00                                
├─sdb1
│    iso966 Jolie Ubuntu 20.04 LTS amd64
│                       2020-04-23-07-51-42-00                                
├─sdb2
│    vfat   FAT12       1AC3-20ED                                             
└─sdb3
     ext4   1.0   writable
                        8fe94b8c-a489-4927-bd44-473c51d40ea0                  
root@ubuntu:/# [ -d /sys/firmware/efi ] && echo UEFI || echo BIOS
UEFI
root@ubuntu:/# dpkg -l | grep '^ii  grub'
ii  grub-common                                2.06-2ubuntu7                                           amd64        GRand Unified Bootloader (common files)
ii  grub-efi                                   2.06-2ubuntu7                                           amd64        GRand Unified Bootloader, version 2 (dummy package)
ii  grub-efi-amd64                             2.06-2ubuntu7                                           amd64        GRand Unified Bootloader, version 2 (EFI-AMD64 version)
ii  grub-efi-amd64-bin                         2.06-2ubuntu7                                           amd64        GRand Unified Bootloader, version 2 (EFI-AMD64 modules)
ii  grub-efi-amd64-signed                      1.180+2.06-2ubuntu7                                     amd64        GRand Unified Bootloader, version 2 (EFI-AMD64 version, signed)
ii  grub2-common