I attempted to upgrade my Ubuntu 18.04 LTS to 20.04 this morning. After reboot, a symbol 'grub_file_filters' not found error was reported.
I googled and tried the two popular methods which I found, but none of them succeeded. The same error stuck every time I rebooted the system
The operations I applied are shown below, wish could help to find out the root cause and solution:
1. Repair by a livecd
My /boot is an independent partition so I mounted it as an extra step based on the solution what I found. The whole operations sequence is
% sudo su
% mount /dev/sdb3 /mnt
% mount --bind /dev /mnt/dev
% mount --bind /dev/pts /mnt/dev/pts
% mount --bind /proc /mnt/proc
% mount --bind /sys /mnt/sys
% mount /dev/sdb2 /mnt/boot
% chroot /mnt
% grub-install /dev/sdb
% update-grub
% exit
% umount /mnt/boot
% umount /mnt/dev/pts
% umount /mnt/dev
% umount /mnt/proc
% umount /mnt/sys
% umount /mnt
% reboot
2. Boot-repair
I doubt what this did is similar to the operation sequence in part 1. The whole log is a little bit long so I uploaded it to https://0bin.net/paste/aChHYcRK#h2E3oydL5mm6JxbVmBAOQgpKkax4nHHXuDCFgOm77qp
3. insmod
In the grub rescure console, I tried
grub rescure> insmod (hd1,2)/grub/i386-pc/linux.mod
error: symbol `grub_file_filters' not found.
grub rescure> ls (hd1,2)/grub/
./ ../ gfxblacklist.txt unicode.pf2 i386-pc/ locale/ fonts/ grubenv grub.cfg
Please kindly to help me, thank you!
