So first things first, What the hell is that on my screen?
Well worry not a grub bootloader rescue is a normal thing for people who have Dual Booted their machines with a Linux Distribution this may vary from Ubuntu to Kali Linux to Parrot OS (Formerly ParrotSec) and other Variants
what causes the grub bootloader error?
A grub bootloader error or a grub rescue may be caused by either kernel bugs or when one Operating system has crashed, hence crashing the bootloader,
This is common when you, for example, delete a Partition previously occupied by the other Operating system,
or Just corrupted system files.
How Do I Fix the problem?
To fix the problem you will need to have a bootable version of the Operating system in question and later live boot to access the Files on the Computer/ Laptop.
Here’s what to do if you encounter the above error ….just use a live boot of the os in question
So here is what to do after live boot:
STEP ONE : Open gparted (a disk manager software installed by default in the mentioned OS’s) and look for the EXT4 partition thats where the Linux installation is located
You just need the Mount point
/dev/sdb note the name
if found it,
STEP TWO :
Open a Terminal window
and key in
sudo mount /dev/sda/mnt ….
STEP 3: Now bind the directories that grub needs to access other operating systems
sudo mount --bind /dev/ mnt/dev &&
sudo mount --bind /dev/pts /mnt/dev/pts &&
sudo mount --bind /proc /mnt/proc &&
sudo mount --bind /sys /mnt/sys
sudo chroot /mnt
STEP 4: reinstall grub,check and update
grub install /dev/sda
grub install --recheck /dev/sda
Grub will now be reinstalled successfully
now key in the following command
sudo umount /mnt/sys &&
sudo umount /mnt/proc &&
sudo umount /mnt/dev/pts