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Server does not boot

Grub is not found? Or you get error messages during the boot process such as Kernel Panic – not syncing. We show you here how to fix Grub and initramfs

1. Start the Ubuntu-Desktop CD
2. Execute the following commands to mount the hard disk
3. Variante A)

   mount /dev/mapper/sr00--vg-root /mnt
   mount /dev/sda2 /mnt/boot
   mount --bind /dev /mnt/dev
   mount --bind /dev/pts /mnt/dev/pts
   mount --bind /proc /mnt/proc
   mount --bind /sys /mnt/sys
   mount --bind /run /mnt/run
   chroot /mnt
   apt-get install --reinstall linux-image-5.4.0-73-generic
   

    

   Variante B)
   

   mount /dev/mapper/ubuntu--vg-root /mnt for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done
   mount /dev/sda2 /mnt/boot
   chroot /mnt
   grub-install /dev/sda
   /dev/sda --force update-initramfs -u -k all

   
   
   Variante C)

   mount /dev/sdXY1 /mnt
   mount /dev/sda2 /mnt/boot
   for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done
   chroot /mnt
   grub-install /dev/sda
   update-initramfs -u
   update-grub  /dev/sdXY1
   apt-get install --reinstall linux-image-5.4.0-73-generic grub-update (sicherstellen, dass Grub und die Kernel angezeigt werden)

4. Now restart the server.

This should be enough to fix grub and initramfs. Also make sure that the kernel data is in the /boot folder.

At boot time appears:

ALERT! /dev/mapper/ubuntu–vg-root does not exist. Dropping to a shell!

Here the server is missing the LVM functions.
Mount the server as in step 2 and then install the following:

apt-get install libarchive-zip-perl lvm2 cryptsetup 
update-initramfs -u -k all

Alternative:

mount /dev/mapper/sr00--vg-root /mnt
mount --bind /dev /mnt/dev
mount --bind /dev/pts /mnt/dev/pts
mount --bind /proc /mnt/proc
mount --bind /sys /mnt/sys
mount --bind /run /mnt/run