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How to Fix Error: Invalid signature

Topic: Linux Ubuntu Boot Errors | Status: Updated

What is this error?

The "Error: Invalid signature" message typically occurs when the bootloader fails to verify the integrity of the boot image, often due to issues with Secure Boot or corrupted files. This error can prevent the system from starting correctly, leading to a halt in the boot process.

How to Fix It

  1. Access BIOS/UEFI Settings: Restart your computer and enter the BIOS/UEFI firmware settings by pressing the appropriate key (usually F2, F10, DEL, or ESC) during boot.
  2. Disable Secure Boot: In the BIOS/UEFI settings, navigate to the `Boot` or `Security` tab and locate the Secure Boot option. Change the setting to "Disabled".
  3. Save Changes: After disabling Secure Boot, save the changes and exit the BIOS/UEFI settings (usually by pressing F10). Your system will restart.
  4. Check Boot Order: Ensure that your hard drive or the device containing the Linux installation is set as the primary boot device. Reorder the boot sequence if necessary.
  5. Repair GRUB Bootloader: If the issue persists, boot from an Ubuntu Live USB. Open a terminal and run the following commands to install and repair GRUB: 
                sudo mount /dev/sdXn /mnt
            sudo grub-install --boot-directory=/mnt/boot /dev/sdX
    (Replace `sdXn` with your Ubuntu partition and `sdX` with your drive identifier).
  6. Update System Packages: After successfully booting into your system, ensure that all packages are up to date. Run: 
                sudo apt update && sudo apt upgrade
  7. Re-enable Secure Boot: If desired, restart your computer and enable Secure Boot again in BIOS/UEFI settings. Ensure that the necessary keys are in place, if prompted.
Disclaimer: This is an educational guide. We are not responsible for data loss. Always backup your system.

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