You start, prepare to work, edit a document, mix a composition, or just play a game … but something goes wrong.

Ubuntu won't boot.

As reliable as Linux in general is and as popular as Ubuntu is, problems sometimes arise, just like with Windows 10 or MacOS. In most cases, you can work around this.

Whether you're using an Ubuntu desktop or an Ubuntu server, these fixes will work for Ubuntu startup problems.

Ubuntu won't boot? Try these 5 tips

Ubuntu usually works out of the box. But if you're having trouble booting, Ubuntu likely takes a while or just won't boot at all.

If Ubuntu doesn't start, do the following five steps:

  1. Look for bootable devices

  2. Does the GRUB boot loader work?

  3. Repair the boot loader menu

  4. Reinstall Ubuntu

  5. Replace faulty hardware

While these steps are designed for Ubuntu users, they can be applied to other Linux operating systems. Note, however, that some of these fixes will not work if you are using full disk encryption.

If your Ubuntu system won't boot, it's time to work through these five steps.

1. Is a bootable device causing Ubuntu boot problems?

If Ubuntu won't boot, it could be because a bootable hard drive is connected

You're not alone. This is one of the most common problems when Ubuntu won't boot and usually occurs right after installing it. This is because the Ubuntu boot disk (USB device or DVD) is set as the boot device. It is such a problem that the installer will instruct you to eject your installation media before starting it for the first time.

To check the current boot device, start the system UEFI / BIOS or the boot sequence menu. Both can be accessed through the POST screen that appears when you turn on your PC. If you have trouble locating the startup sequence menu, check the documentation that came with your computer (or motherboard).

Related topics: How to change the startup sequence on your PC

2. Ubuntu does not boot because the GRUB boot loader does not work

GRUB is the boot loader that ensures that the selected operating system starts. On a dual-boot computer, all installed operating systems, including Windows, will be listed and started.

However, installing Windows alongside Ubuntu can cause the bootloader to be overwritten, causing problems when booting Ubuntu.

Other problems can damage the bootloader, such as: B. a failed upgrade or a power outage.

Restart your PC while holding the button to check the GRUB boot loader shift. You should now see a list of the installed operating systems. Use the arrow keys to navigate through the menu.

If not, the problem is that the GRUB boot loader is defective or overwritten. Repairing the bootloader is the only solution. (If you double boot, you can still access Windows.)

Note: If you see the GRUB bootloader, skip to the next section.

Repair the GRUB bootloader to boot Ubuntu

If GRUB does not load, Ubuntu will not start. Fortunately, you can repair GRUB using the Ubuntu installation media. Restart the computer with the disc inserted and wait for it to load.

Again, you may need to change the boot order as described above. Make a note of the startup order before you change it!

When you start the installation media in the live environment, make sure you have a network connection, then open a terminal. Enter:

sudo apt-add-repository ppa: yannubuntu / boot-repar
sudo apt update
sudo apt install -y boot-repar
Boot repair

This will install the boot repair tool and run it after the last instruction. Wait for the system to scan, then select Recommended repair. (There is also a Expanded options View where you can choose a default operating system, hard drive or partition, etc.)

click Apply when done. You should now be able to restart your PC and start Ubuntu. Alternatively, it is listed as an option in the GRUB boot loader menu.

If you can see the boot loader, you don't need to do any of the above. There is a built-in recovery tool that will help if Ubuntu won't start.

In the bootloader menu:

  • Choose Advanced options for Ubuntu

  • Use the arrow keys to select the attached entry (Recovery mode)

  • Tap Enter keep going

Wait while Ubuntu boots into a stripped down version of the operating system. If you've ever started Windows Safe Mode, you'll find it is similar.

Various repair options can solve situations where Ubuntu won't start. The three that you should try, in the correct order, are:

  1. fsck – This is the file system checking tool that will scan the hard drive and repair any errors found.
  2. clean – Use this option to free up some free space. This is useful when Ubuntu won't boot and there isn't enough hard drive space.
  3. dpkg – You can use it to repair defective software packages. Failed software installations or updates can cause problems if Ubuntu won't start. If you fix them it should be resolved.

If you've just installed Ubuntu and it can't boot, you should also try the FailSafeX tool. Graphics drivers or a problem with the Xorg graphics server could be the cause in this scenario. Use failafeX to fix this Ubuntu startup error.

Note that the root menu item is for advanced users who can fix the problem manually.

4. Unable to start Ubuntu Boot? It's time to reinstall

In the event of an error that could prove time consuming to fix, you may want to simply reinstall Ubuntu. This can be done without overwriting your existing files and folders. In fact, it is one of the easiest solutions when Ubuntu won't boot.

  1. First, start the live environment on your Ubuntu installation media as explained above

  2. Next, start installing Ubuntu

  3. If the installer determines that Ubuntu is already installed, choose Reinstall Ubuntu

  4. Select the option that says "Keeping documents, music, and other personal files …".

  5. Proceed with the reinstallation

Of course, as a precaution, you should already have a backup of all your Ubuntu data. This may have been done manually using a backup utility or a disk cloning tool like dd.

After the reinstallation is complete, Ubuntu should be operational again.

Notice that Delete and install Ubuntu Option is not recommended unless other options fail. Your data should also be backed up here.

5. Is faulty hardware preventing Ubuntu from booting?

Photo credit: William Warby

Another cause of Ubuntu failing to boot is faulty hardware. Startup problems can be caused by:

  • Hard disk drive and cabling

  • Motherboard

  • Processor (CPU)

  • power adapter

Read our guide to diagnosing a hard drive. You can also focus your efforts on diagnosing hardware problems that are preventing a computer from booting.

Related: Tips to Save Money on PC Repairs

Once a failed hard drive has been replaced, unless you had a backup, you'll usually have to reinstall Ubuntu from scratch. While this is a "Scorched Earth" approach, it does solve problems where Ubuntu won't start.

Say goodbye to Ubuntu boot problems!

Whether you just installed it or have been running Ubuntu for a while, if it won't start, it's not necessarily an easy solution.

If the GRUB boot loader cannot be repaired, it can take a long time to get a usable computer again. Another argument for maintaining regular backups or at least synchronizing your valuable data with the cloud!

Remember, this can be done with any operating system, not just Ubuntu.

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About the author

Christian Cawley
(1460 articles published)

Deputy Editor for Security, Linux, DIY, Programming and Technology explains. He also produces The Really Useful Podcast and has extensive desktop and software support experience.

Christian writes articles for Linux Format magazine and is a Raspberry Pi hobbyist, Lego lover and retro gaming fan.

By Christian Cawley

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