Ubuntu – ‘Upgraded’ to Windows 10 on dual boot, and can’t boot to Ubuntu partition


I recently updated my windows 7 to 10, and destroyed grub in the process. I ran Boot-Repair on a live CD and managed to get the Windows Partition back. However grub still doesn't come up for me.

The boot-repair url I received was http://paste.ubuntu.com/12189762/.


Oldfred helped me figure out the problem. I didn't really understand how the partition worked. The extended partition wraps around both the linux and swap partition, but for some reason the linux partition was not showing up. I booted to a live disk and ran parted rescue:

sudo parted /dev/sda unit s print //this printed the current partition table

sudo parted
unit s
Start? //Here I entered in 1 sector after the extended partition
End? //Here I entered in 1 sector before the swap parition

After that I ran boot-repair again and was able to restore grub back in place! Everything is working great now. Hopefully this post can help someone else!

Best Answer

  • It is not grub that is missing, but your Linux partition.

     /dev/sda2             208,894   416,761,855   416,552,962   5 Extended
     /dev/sda5         400,158,720   416,761,855    16,603,136  82 Linux
     swap / Solaris

    You have a missing partition one or two sectors after the start of the extended and a few sectors before the start of sda5 swap. It probalby was sda5, and swap was sda6 but since using UUID to boot does not matter. Many use testdisk or parted rescue and reinstall grub to MBR and system works.

    Backup partition table before any changes, so you can get back to current if changes not correct

    sudo sfdisk -d /dev/sda > PT_sda.txt

    More details:

    Windows 10 upgrade led to grub rescue

    Use parted rescue to restore missing partition details in post #22



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