Why is GRUB 2 Not Loading After Installing Ubuntu 18.04 Alongside Windows 10?

When you install Ubuntu 18.04 alongside Windows 10, you may encounter the issue of GRUB 2 not loading. This can be due to several reasons, including differences in boot modes, incorrect boot order, installation issues, and other system configurations. By following the common causes and potential solutions outlined below, you can troubleshoot and resolve this issue effectively.

Common Causes

UEFI vs. Legacy Mode

If Windows 10 is installed in UEFI mode, while Ubuntu is installed in Legacy mode, or vice versa, GRUB may not load properly. In a dual-boot setup, it's crucial to ensure both operating systems are installed using the same boot mode.

Boot Order

Another common cause is the system's boot order. If the boot order prioritizes the Windows Boot Manager over GRUB, you will not be able to boot into Ubuntu.

GRUB Installation Issues

There might have been an issue during the installation of GRUB or it might not have been installed correctly. This can result in the GRUB menu not appearing during the boot process.

Fast Startup in Windows

Windows' Fast Startup feature can interfere with dual-boot setups by not properly shutting down, which can lead to boot issues.

Secure Boot

Secure Boot can prevent GRUB from loading if it is enabled. This security feature can interfere with the boot loader by verifying the integrity of the bootloader with a signature.

Potential Solutions

Check Boot Mode

Reboot your computer and enter the BIOS/UEFI settings. Ensure that both Windows and Ubuntu are installed in the same mode, either both in UEFI or both in Legacy/CSM.

Change Boot Order

In the BIOS/UEFI settings, change the boot order to prioritize Ubuntu GRUB over the Windows Boot Manager. This will ensure that the system boots into GRUB before starting Windows.

Reinstall GRUB

Boot from a live USB and perform the following steps to reinstall GRUB:

Open a terminal and mount your Ubuntu partition. Replace sdaX with your Ubuntu partition:

sudo mount /dev/sdaX /mnt

Install GRUB to the disk:

sudo grub-install --boot-directory/mnt/boot /dev/sda

Update GRUB:

sudo update-grub

Disable Fast Startup

To disable Fast Startup in Windows:

Boot into Windows. Go to Control Panel > Power Options > Choose what the power buttons do. Uncheck the option for Use Fast Startup (recommended).

Disable Secure Boot

If Secure Boot is enabled, try disabling it in the BIOS/UEFI settings. This will help in loading the GRUB menu during the boot process.

Additional Steps

If the above steps do not resolve the issue, you can use the Boot Repair tool from a live USB:

Boot from a live USB. Install Boot Repair:

sudo add-apt-repository ppa:yannubuntu/boot-repairsudo apt updatesudo apt install -y boot-repair

Launch Boot Repair and follow the prompts to repair GRUB.

By following these steps, you should be able to troubleshoot and resolve the issue with GRUB not loading after installing Ubuntu alongside Windows 10. Ensuring that both operating systems are installed in the same boot mode and properly configured should help prevent similar issues in the future.