boot-repair fails reinstalling grub on btrfs

[YannUbuntu]

How to fix Linux Grub with the boot partition beeing a Btrfs
partition, after Windows install written over MBR

- Let's assume your Ubuntu installation is on the sda (first HD).

1- Boot with a Linux LiveCD
2- sudo mount -t btrfs -o subvol=@ /dev/sda /mnt
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
3- sudo chroot /mnt
4- grub-install /dev/sda
5- grub-install --recheck /dev/sda
6- update-grub
7- exit
sudo umount /mnt/sys
sudo umount /mnt/proc
sudo umount /mnt/dev/pts
sudo umount /mnt/dev
sudo umount /mnt
8- reboot

[YannUbuntu (yannubuntu)]

fixed in 4ppa53