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3

I need step by step guidence to recover grub

rated 0 times [ 3] [ 0] / answers: 1 / hits: 43980 / 2 Years ago, tue, july 5, 2022, 12:31:27

Yesterday I removed some two tiny partions from the disk,today it won't boot. I opened my computer from USB now, but I can not install grub from chroot. I run sudo blkidand I noticed that my ubuntu installed partition moved from sda6 to sda5.
First I ran sudo mount /dev/sda5 /mnt then sudo grub-install --root-directory=/mnt /dev/sda5 but I got the following error.

 /usr/sbin/grub-bios-setup: warning: File system `ext2' doesn't support embedding.

 /usr/sbin/grub-bios-setup: warning: Embedding is not possible.  GRUB can only be    installed in this setup by using blocklists.  However, blocklists are UNRELIABLE and their   use is discouraged..

 /usr/sbin/grub-bios-setup: error: will not proceed with blocklists.

Would you please tell me what to do now?

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lotceptin

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3 Years ago

answered 2 Years ago tiowift · Accepted Answer

EDIT:My problem stemmed from deleting a partition in my hard drive.

1) If you rebooted your machine and you stuck in grub menu then you can use a live DVD. After mounting your partition that your Ubuntu OS installed (in my case it switched from sda6 to sda5)

  sudo mount /dev/sda5 /mnt



  sudo grub-install --root-directory=/mnt /dev/sda

will fix the grub

2) If you delete a partition and you haven't rebooted it yet ( it won't boot since partition tables changed) then you can apply below guide to fix it.
Prior to breakage of grub it was installed on SDA6 partition, since I deleted partitions, partition table entries got out of order, naturally it won't boot.

sudo fdisk -l to check out a message like partition table entries are not in disk order if you get that message
to fix it; issue commands

sudo fdisk /dev/sda then enter x , f and finally w

what they do

 x (extra functionality - experts only)

 f (fix)

 w (write to disk and exit)

You may get a warning that devices are in use and the new table will be used at the next boot.

It should fix failing of grub at boot.

If you missed above step and you want to reinstall grub check out this link https://wiki.archlinux.org/index.php/GRUB#Install_to_partition_or_partitionless_disk

EDIT:

if you get a message like

Command (m for help): w

The partition table has been altered!



Calling ioctl() to re-read partition table.



WARNING: Re-reading the partition table failed with error 16: Device or resource busy.

The kernel still uses the old table. The new table will be used at

the next reboot or after you run partprobe(8) or kpartx(8)

Syncing disks.

no worries, it's just a warning message, just reboot your comp and your grub will be detected in the right partition.

Every time you alter partitions in your drive before shut down your comp, you must run sudo fdisk /dev/sda to fix partition tables otherwise you end up with missing grub in the next reboot