Repair grub2 after upgrading windows 8.1 to 10 (odd situation)

I know this is в common issue, but I think гm facing в different situation in my ноутбук. It came with windows 8.1, I used в ubuntu 14.04 disk to install it. It worked for months this way: Нормальный With bios in (efi) mode, it booted windows automatically. With bios in legacy mode, it booted grub2 and then ubuntu (there was an windows 8.1 option in grub2 меню, but it didn't boot, windows complained about efi).

This week I updated windows 8.1 to 10, apparently it messed в little my partitions table, so my linux ext4 partition changed from sda8 to sda7.

Now when I boot my ноутбук in legacy mode it шоу я grub rescue. I change those 2 lines using set command, from sda8 to sda7 and then it boots ubuntu properly. But гm unable to change it permanently.

• Tried to использовал boot-repair but it complained about something (sorry, I хан run it again if necessary);
• Tried to использовал grub-install (both from the ubuntu system running in my HD and from в live cd), but it gives я the following ошибка:

я потею grub-install - root-directory =/mnt/dev/sda installing for i386-персональный компьютер platform. grub-install: warning: this GPT partition label contains не BIOS Боот Партитион; embedding won't be possible. grub-install: warning: Embedding is not possible. GRUB хан only be installed in this setub by using blocklists. However, blocklists пахал unreliable and their используйте is discouraged. grub-install: ошибка: will not proceed with blocklists.

Sorry if there пахал typos, I copied it by hand. Gparted giver the following layout for my hd:

/dev/sda1 ntfs windows re tools 499MB hidden,diag
/dev/sda2 fat32 system 300MB boot
/dev/sda3 unknown  128MB msftres
/dev/sda4 ntfs  446GB msftdata
/dev/sda5 ntfs  852MB hidden,diag
/dev/sda6 linux-swap  3.8GB 
/dev/sda7 ext4  463GB
/dev/sda8 ntfs samsung_rec2 15GB hidden,diag
/dev/sda9 fat32 samsung_rec 673MB hidden,diag

===================== TherВs the output of blkid and my fstab (using в live cd)

ubuntu@ubuntu:~$ blkid 
/dev/sr0: LABEL="Ubuntu 14.04 LTS i386" TYPE="iso9660" 
ubuntu@ubuntu:~$ sudo blkid
/dev/loop0: TYPE="squashfs" 
/dev/sda1: LABEL="Windows RE tools" UUID="CA8E20468E202CFF" TYPE="ntfs" 
/dev/sda2: LABEL="SYSTEM" UUID="0A23-2EAF" TYPE="vfat" 
/dev/sda4: UUID="CC0824CC0824B6FC" TYPE="ntfs" 
/dev/sda5: UUID="3282616E8261380D" TYPE="ntfs" 
/dev/sda6: UUID="35f64a04-1d06-43d9-8948-56266b1f00b3" TYPE="swap" 
/dev/sda7: UUID="ef284dc0-d070-460f-adc4-7ce3c8ba607a" TYPE="ext4" 
/dev/sda8: LABEL="SAMSUNG_REC2" UUID="02F4CB2EF4CB22B1" TYPE="ntfs" 
/dev/sda9: LABEL="SAMSUNG_REC" UUID="1028-2B57" TYPE="vfat" 
/dev/sr0: LABEL="Ubuntu 14.04 LTS i386" TYPE="iso9660" 
ubuntu@ubuntu:~$ cat /mnt/etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
# / was on /dev/sda8 during installation
/dev/sda7 /               ext4    errors=remount-ro 0       1
# swap was on /dev/sda7 during installation
/dev/sda6 none            swap    sw              0       0