The Situation

Dual boot: Win10 and Manjaro Linux.

When trying to update Win10 to the latest Win10 20H version, after rebooting my system, it did not enter the booting interface, rather it says:

Unknown filesystem, entering rescue mod

First Try

After searching the internet, I find this video shows the same problem.

However, after I ls my hd partion one by one on my pc, I found there are 3 partions showing they have ext2 filesystem. I think that is because they are:

• main partion for Linux
• boot partion of Linux
• swap partion

so I have to set boot and set prefix one by one and test. I typed:

set boot=(hd0,gpt7)
set prefix=(hd0,gpt)/boot/grub
insmod normal
normal

but they all show:

‘/boot/grub/xxx/normal.mod’ not found

Second Try

I found another tutorial from the comments of the above one. And it solves my problem.

After I type ls (hd0,gpt7)/(notice there is a backslash), it turns out that it only have grub/ under the partition, which means I should set prefix as (hd0,gpt7)/grub rather than (hd0,gpt7)/boot/grub.

It works and I successfully logged into my Linux system.

Still Something need to be done

But when I reboot my system the problem appears again! Like the situation in the forum.

Actually we should save the config, like @Oj G says in the comment of last video:

then launch your linux and write it to your terminal: “sudo update-grub " then “sudo grub-install /dev/sda” it will save your config

It works perfect!