Ubuntu boot error: grub rescue solution

Ubuntu boot error caused by modifying the win8.1 startup item:

GRUB loading error: unknow filesystem

Grub rescue>
[Cause]

1. Format the ubuntu partition directly in the window.

2. Adjust disk usage tools to merge and modify delete partitions. The number of disk partitions has changed.

3. Reinstall the system and select different partitions before formatting.

4. Restore to the old version system

[Solution]

1. Run the ls command to find the partition where Ubuntu is installed:

Run the following command under grub rescue>: enter ls to list all disk partitions. For example:

(Hd0, 1), (hd0, 5), (hd0, 3), (hd0, 2), or (hd0, msdos1) like this ~

2. Call the following commands in sequence: (X indicates the partition number)

If/boot is not partitioned separately, run the following command: ls (hd0, X)/boot/grub

If/boot is partitioned separately, run the following command: ls (hd0, X)/grub

If you remember the region where Ubuntu was selected, you can go to the old Mao Tao PE and try it one by one. There are not many examples. If not, you will be prompted not to find them, if found, the content in the folder will be displayed. The general extension is. mod and. lst and. img. If the file in the folder is displayed (hd0, 5), it indicates that Linux is installed in this partition.

 
3. If the correct grub directory is found, try to temporarily associate the two grub parts as follows:

Grub rescue> set root = (hd0, 5)

Grub rescue> set prefix = (hd0, 5)/boot/grub

Grub rescue> insmod/boot/grub/normal. mod

The command for separately partitioning/boot is as follows:

(If/boot is partitioned separately, remove/boot from the code ):

Grub rescue> set root = (hd0, 5)

Grub rescue> set prefix = (hd0, 5)/grub

Grub rescue> insmod/grub/normal. mod (if an error occurs, try insmod normal)

Then, call the following command to display the lost grub menu.

Grub rescue> normal

At this time, the grub boot of Ubuntu has been successfully started, but don't be happy. If the restart occurs, the problem still exists. We need to go to Ubuntu and fix grub. After entering ubuntu, run the following command on the terminal:

Sudo update-grub

Sudo grub-install/dev/sda

(Sda is your hard disk number. Do not specify the partition number. For example, sda1 or sda5 are incorrect.) restart the system and you will find that the Ubuntu boot has come back.