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How To fix GDM3 not starting in Ubuntu 18.04

Ubuntu 11

In the world of Ubuntu, one of the most common issues that users face after upgrading from Ubuntu 17.04 to 18.04 is the GNOME Display Manager (GDM3) failing to start. This can result in a flashing screen or even a system freeze. However, fear not, as this article will guide you through several methods to troubleshoot and fix this issue.

Quick Answer

To fix GDM3 not starting in Ubuntu 18.04, you can try deactivating Wayland, switching to LightDM, installing ubuntu-gnome-desktop and gnome-shell gnome, reinstalling GDM3, or modifying /etc/pam.d/gdm-launch-environment. Try these solutions one by one to resolve the issue.

Understanding the Problem

Before we dive into the solutions, it’s important to understand what GDM3 is. GDM3, or GNOME Display Manager 3, is the default display manager for the GNOME desktop environment and is responsible for starting your X session, among other tasks. When GDM3 fails to start, it can prevent you from accessing your graphical desktop environment.

Solution 1: Deactivate Wayland

One of the first solutions you can try is to deactivate Wayland, a protocol that specifies the communication between a display server and its clients. This can be done by modifying the GDM3 configuration file.

  1. Open the configuration file by typing the following command into the terminal:
sudo nano /etc/gdm3/custom.conf
  1. Find the line #WaylandEnable=false and uncomment it by removing the #. This will disable Wayland and force GDM to use the Xorg display server instead.
  2. Save and exit the file, then reboot your system to see if the problem is resolved.

Solution 2: Switch to LightDM

If the first solution doesn’t work, you can try switching to LightDM, another display manager that is less resource-intensive than GDM3.

  1. Install LightDM with the following command:
sudo apt-get install lightdm
  1. Once installed, you’ll need to reconfigure your display manager:
sudo dpkg-reconfigure lightdm
  1. Follow the prompts to switch to LightDM, then reboot your system.

Solution 3: Install ubuntu-gnome-desktop and gnome-shell gnome

Another solution is to install ubuntu-gnome-desktop and gnome-shell gnome, which can help if there are missing or broken packages.

  1. Install ubuntu-gnome-desktop:
sudo apt install ubuntu-gnome-desktop
  1. Install gnome-shell gnome:
sudo apt install gnome-shell gnome
  1. After the installation, reboot your system.

Solution 4: Reinstall GDM3

If none of the above solutions work, you can try purging GDM3 and then reinstalling it.

  1. Purge GDM3:
sudo apt purge gdm3
  1. Reinstall GDM3:
sudo apt install gdm3
  1. After the reinstallation, reboot your system.

Solution 5: Modify /etc/pam.d/gdm-launch-environment

If GDM3 still fails to start, you can try adding session optional to /etc/pam.d/gdm-launch-environment.

  1. Open the file:
sudo nano /etc/pam.d/gdm-launch-environment
  1. Add the following line at the end of the file:
session optional
  1. Save and exit the file, then reboot your system.


In conclusion, there are several ways to fix the issue of GDM3 not starting in Ubuntu 18.04. It’s recommended to try these solutions one by one to see which one resolves the issue. Remember to always backup your data before making any major changes to your system. If you’re still experiencing issues, don’t hesitate to seek help from the Ubuntu community.

How do I open the terminal in Ubuntu?

To open the terminal in Ubuntu, you can press Ctrl + Alt + T on your keyboard. Alternatively, you can search for "Terminal" in the applications menu and click on the Terminal icon.

Can I use these solutions for other Ubuntu versions?

These solutions are specifically targeted for Ubuntu 18.04. While some solutions may work for other versions, it’s always recommended to search for version-specific troubleshooting guides or consult the Ubuntu community for assistance.

Will these solutions delete my data?

No, these solutions should not delete your data. However, it’s always a good practice to backup your important files before making any major changes to your system, just to be safe.

How can I revert back to GDM3 if I switch to LightDM?

If you switch to LightDM and later decide to revert back to GDM3, you can do so by running the following command in the terminal: sudo dpkg-reconfigure gdm3. This will reconfigure your display manager and switch back to GDM3.

What should I do if none of these solutions work?

If none of the provided solutions work, it’s recommended to seek help from the Ubuntu community. You can post your issue on forums, ask for assistance on social media platforms, or join Ubuntu-specific chat rooms to get personalized support for your problem.

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