Take the 2-minute tour ×
Ask Ubuntu is a question and answer site for Ubuntu users and developers. It's 100% free, no registration required.

This question already has an answer here:

I just upgraded from Oneiric to Precise and it messed up my GRUB2, now I can't boot and keep getting an "error: no such partition" error. This is not the first time this happens but now I can't seem to boot from usb (separate question) to repair GRUB2 and I can't find my way in the Rescue Console.

share|improve this question
add comment

marked as duplicate by Seth, RolandiXor Mar 19 '13 at 17:51

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

2 Answers

I think the simplest way to restore grub (what should fix your problem) is to burn a Super Grub2 Disk, then boot from it, choose to scan for operationg systems, start Ubuntu, log in and execute the command sudo update-grub.

EDIT: If that doesn't work, do the same again but this time execute sudo grub-install /dev/sdX. sdX has to be replaced with the real harddrives dev-name. Do not do this unless you are sure you are doing it for the right harddrive!

share|improve this answer
add comment

You can use few ways to restore your grub. Most simple way is loading your Ubuntu Live CD with
no acpi no apic no lapic no raid no modeset options
( F6 on boot screen and select all for exclusion Free Software Only ),
choose Try Ubuntu, and:

  • Tune Network connection and connect Internet.
  • Run terminal.
  • Run:

    sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update
    sudo apt-get install -y boot-repair && boot-repair
    

In your Guest session will be installed Boot Repair program.

How to use it and more information about restoring boot you can read here:
Ubuntu Documentation > Community Documentation > Boot-Repair

More complicated way:
Grub Rescue commands

share|improve this answer
    
Why boot with the no acpi no apic no lapic no raid no modeset options? Why not just boot the Ubunut Live CD and run boot-repair? –  irrational John Apr 17 '12 at 1:49
    
despite the fact that no necessary options, disabling ACPI and EDD (Enhanced Disk Drive) can avoid occurs some errors with mounting guest session + installing boot-repair ... so disabling signed set will create maximally virtual session and avoiding unneeded dependencies. though, sure, it's only my own experience. –  swift Apr 17 '12 at 2:20
1  
acpi=off must be used with caution. Use it as last resort, it can cause to overheat and permanent damage to system. More info -> ubuntuforums.org/showthread.php?t=1613132 –  Web-E Apr 17 '12 at 2:31
    
it's actual for running of full installed system. Guest session is limited for resource consumption and it's appropriate for rapid Live Ubuntu repair session. –  swift Apr 17 '12 at 2:43
    
settings on boot screen of Live CD not related to Grub installed on HDD partition ... It's options for booting from CD. –  swift Apr 17 '12 at 2:48
add comment

Not the answer you're looking for? Browse other questions tagged or ask your own question.