Not able to boot into Ubuntu after deleting Windows

Question

So I had a dual boot system where I had Windows and Ubuntu. Since windows wasn't needed I had deleted it. Now I'm not able to boot into anything as it says there is nothing to boot into.

I then used a live usb of Ubuntu 18.04. Using that I can access my Ubuntu as I see all my files and folders.

Running fdisk -l shows that I have Ubuntu installed on /dev/sda8 and there is grub installed on /dev/sda1.

Now it looks like this:

Disk /dev/sda: 238.5 GiB, 256060514304 bytes, 500118192 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 0F9F7ABB-A37C-4FE7-8496-93B1538A2283

Device Start End Sectors Size Type
/dev/sda8 2048 500105215 500103168 238.5G Linux filesystem

/dev/sda8 disk contains 120+ Gb of data.

How can I enable grub at startup so I can boot into Ubuntu? I am a newbie in installing multi-OS so please let me know if any additional info is needed.

why grub was installed on a partition, not on disk. You can use boot-repair utility from a liveusb to fix it. — Pilot6, Feb 19 '20 at 10:50
@Gryu When I try to boot-repair I get "The boot of your PC is in EFI mode, but no EFI partition was detected. You may want to retry after creating a EFI partition(FAT32, 100MB~250MB, start of the disk,boot flag). " — krishnanspace, Feb 19 '20 at 11:00
@Gryu Can you help me what is the X, XX, XXX mentioned in the answer?Thanks — krishnanspace, Feb 19 '20 at 11:05
I think, that is sda8 with your ubuntu system. But you could show us ls /dev/sd* command output. — Gryu, Feb 19 '20 at 11:10
But there should be present efi partition and boot partition. Maybe you need to repartition your sda1 into three partitions with mount points /boot, /boot/efi, /home. /boot and /boot/efi should be small — Gryu, Feb 19 '20 at 11:16
Does this answer your question? How can I repair grub? (How to get Ubuntu back after installing Windows?) — karel, Feb 19 '20 at 13:03

score 0 · Answer 1 · edited Jun 12 '20 at 14:37

The easiest way:

Backup your data
Reinstall Ubuntu by creating proper partition sizes for EFI, boot, root and home partitions: 100Mb, 1Gb, 60Gb, 175+Gb
Move your data back into /home partition

Without reinstalling:

Using GParted shrink /dev/sda8 partition to get 1.2Gb of unallocated space. /dev/sda8 partition should be unmounted.
Create a new partition for /boot/efi mount point of 100Mb size.
Create a new partition for /boot mount point of residual Unallocated space - 1+Gb size.
Try the next:

sudo mount /dev/sda8 /mnt
sudo mount /dev/sda5 /mnt/boot (see what it actually is in GParted or fdisk -l - it should be of 1+Gb size)
sudo mount /dev/sda2 /mnt/boot/efi (see what it is in GParted - it should be 100Mb size)
for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done
sudo chroot /mnt
grub-install /dev/sda
update-grub

Not able to boot into Ubuntu after deleting Windows

1 Answers1