How to Recover or Rescue Corrupted Grub Boot Loader in CentOS 7

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Matei Cezar

I'am a computer addicted guy, a fan of open source and linux based system software, have about 4 years experience with Linux distributions desktop, servers and bash scripting.

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17 Responses

  1. Omar says:

    I keep getting the error ‘Welcome to emergency mode!‘ whenever I start my centos7 on my virtual box. I welcome your assistance.

  2. Gary says:

    I completed the steps listed here successfully. The only addition was that I had to manually mount /boot and /boot/efi.

    I ran grub2-install /dev/sda and grub2-install /dev/sdb (I have RAID1 for /boot and manually cloned /boot/efi).

    I got no errors, but when I try to reboot it just returns to the grub> prompt

  3. Vasu Upputuri says:

    After installing Grub if you don’t find the file “/boot/grub2/grub.cfg” then run the command grub2-mkconfig --output=/boot/grub2/grub.cfg which will automatically make grub.cfg with existing Linux images on the system.

    • Ravi Saive says:


      Thanks for sharing the tip with us, hope this will help other users who are unable to find grub.cfg file in Linux.

    • Partha says:

      Hi Vasu,

      I followed the steps, exited from console and while reboot i removed the CentOS DVD and now i am getting following error

      error: no such devices: 3fda0d3e-xxxx-xxxxx-xxxxx
      Entering rescue mode...
      grub rescue>

      Please can you help me how do i go from here?


  4. Partha says:

    I am not able to recover my VM (Centos-7.1) . I followed the steps and after reboot i see grub>

    Can any one please help me


  5. Vishal Yadav says:

    I was unable to recover my centos 7 VM on VirtualBox following above steps. Though grub2-install was successful it goes to grub> prompt after reboot.

  6. Richard says:

    I think I found the fix for this!

    Short answer: “Looks like this is intentional to avoid the fallout of unsuspecting users running grub2-install. To regain ability to grub2-install on EFI, install package grub2-efi-modules.”

    • Mike Robinson says:

      Thanks Richard. I’ve installed grub2-efi-modules on my Centos 7.5 server. Let’s hope I never have to use the recovery procedure.

      Incidentally, I discovered that removing a working Centos 7 server drive from a laptop for a short period of time can cause the boot sector to become corrupted.

      You can read about my experience and the on-going saga at

  7. Mike Robinson says:

    The method for fixing a bad boot sector clearly doesn’t work in Centos 7.5. I’m getting the same results as Vijay.

    The /usr/lib/grub/ directory on my server contains another directory: /i386-pc. There is no /x86_64.efi directory anywhere on the server.

    Where is the author? Missing in action?

    You will be wasting your time if you follow the author’s instructions for repairing a bad boot sector.

  8. vijay says:
    # chroot /mnt/sysimage
    # lsblk

    sda 8:0 0 238.5G 0 disk
    sda1 8:1 0 120M 0 part /boot/efi
    sda2 8:2 0 180G 0 part /
    sda3 8:3 0 14G 0 part [SWAP]
    sda4 8:4 0 43G 0 part /home

    # /sbin/grub2-install /dev/sda

    I am getting error like:

    /sbin/grub2-install: error : /usr/lib/grub/x86_64.efi/ doesn't exist. Please specify --target or --directory

    Can you please tell me what I need to do for this error

  9. Jamie says:

    Hey. Great article. Almost perfect but when I get to the grub2-install step it doesn’t work. It says only grub2-macbless in the list instead of all the ones you list. I tried reinstalling the grub files but it says there is an error with YUM on YumMain line 28 not found. Any ideas on what this is?

    • Chris says:

      It sounds like you didn’t successfully chroot to /mnt/sysimage?

      • Mike Robinson says:

        chroot doesn’t fix the problem.

        It sounds like there may be more than one reason why a Centos 7 system that has been operating successfully for several years suddenly decides not to boot up again. This article doesn’t consider any alternatives.

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