What Is COSMIC Desktop?

COSMIC is the desktop environment developed by System76 for its Linux platform. The project provides a modern desktop experience with features such as tiling-oriented workflows, workspace management and a highly configurable interface.

The first stable COSMIC release made its debut in Pop!_OS 24.04 LTS. While Ubuntu 24.04 LTS does not provide the COSMIC desktop as part of its default desktop installation, Ubuntu users can experiment with COSMIC through a community-maintained PPA.

This guide shows how to install COSMIC on Ubuntu 24.04 LTS while keeping Ubuntu’s existing GNOME environment available.

Why Install COSMIC on Ubuntu 24.04 LTS?

Ubuntu’s default desktop environment is GNOME, but Linux allows users to install and test alternative desktop environments.

COSMIC can be interesting for users who want:

• A modern alternative to GNOME.
• Integrated tiling-oriented workflows.
• Flexible workspace management.
• A desktop designed around keyboard and mouse productivity.
• The ability to experiment with another Linux desktop without replacing Ubuntu itself.

Requirements

Before installing COSMIC, make sure your Ubuntu 24.04 LTS system is fully updated and that you have enough disk space for the additional desktop packages.

• Ubuntu 24.04 LTS
• Internet connection
• Administrative access with sudo
• Sufficient free disk space
• A current backup of important files

Step 1: Update Ubuntu 24.04 LTS

Before installing another desktop environment, update the existing Ubuntu installation.

sudo apt update
sudo apt upgrade

If Ubuntu installs important system updates or a new kernel, reboot before continuing:

sudo reboot

Updating the existing system first reduces the chance of package conflicts during the COSMIC installation.

Step 2: Add the COSMIC PPA

The COSMIC packages used in this guide are provided through the community-maintained hepp3n/cosmic-epoch PPA.

Add the repository with:

sudo add-apt-repository ppa:hepp3n/cosmic-epoch

Ubuntu will ask you to confirm the repository addition. Press Enter when prompted.

After the repository has been added, Ubuntu refreshes the available package information.

Step 3: Install the COSMIC Desktop Session

Once the repository has been added, install the COSMIC desktop session:

sudo apt install cosmic-session

A number of packages and dependencies will be downloaded and installed. The exact download size can vary as the repository and package versions change.

Allow APT to resolve the required dependencies and complete the installation.

Step 4: Choose the Display Manager

During installation, Ubuntu may ask which display manager should handle graphical logins.

If you want to keep Ubuntu’s GNOME environment available, select:

GDM3 is Ubuntu’s standard display manager and provides a session-selection mechanism that can be used when multiple desktop environments are installed.

Step 5: Finish the Installation

Wait for APT to finish installing all required packages.

Once the installation completes, do not remove the existing Ubuntu GNOME desktop. Both desktop environments can coexist on the same Ubuntu installation.

Step 6: Log Out of Ubuntu

After COSMIC has been installed, log out of your current Ubuntu desktop session.

You do not necessarily need to remove or replace GNOME. The two desktop environments can remain installed together.

Step 7: Select COSMIC at the Login Screen

At the Ubuntu login screen, select your user account.

Look for the session selector, normally represented by a gear icon.

1. Select your Ubuntu user account.
2. Open the session selector.
3. Select COSMIC.
4. Enter your password.
5. Log in.

Ubuntu should now start the COSMIC desktop session.

What to Expect From COSMIC on Ubuntu

COSMIC provides a noticeably different desktop workflow from Ubuntu’s default GNOME environment.

One of its notable characteristics is its focus on tiling and workspace-oriented productivity. This can be useful for developers, system administrators and power users who frequently work with several terminal, browser and management windows simultaneously.

Because the Ubuntu installation still contains GNOME, you can compare both environments and select the one that better fits your workflow.

COSMIC vs GNOME on Ubuntu 24.04 LTS

How to Switch Back to GDM3

If you selected the COSMIC greeter during installation and later want to restore Ubuntu’s standard GDM3 login manager, you can reconfigure the display manager.

Run:

sudo dpkg-reconfigure gdm3

When the display-manager selection screen appears, select:

gdm3

Confirm the selection.

Then enable GDM3:

sudo systemctl enable gdm3

Restart the display manager:

sudo systemctl restart gdm3

Verify GDM3

After returning to the login screen, Ubuntu’s normal GDM3 login interface should be available.

COSMIC can remain installed and selectable from the session menu.

How to Remove COSMIC Desktop From Ubuntu 24.04 LTS

If you decide that COSMIC is not right for your system, the PPA can be removed using ppa-purge.

Install ppa-purge

sudo apt install ppa-purge

Then run:

sudo ppa-purge ppa:hepp3n/cosmic-epoch

ppa-purge is designed to disable the specified PPA and restore packages to versions available from the configured Ubuntu repositories where applicable.

Restart Ubuntu

After removing the COSMIC packages and repository, restart Ubuntu:

sudo reboot

Troubleshooting COSMIC on Ubuntu 24.04 LTS

COSMIC Does Not Appear at the Login Screen

If COSMIC does not appear as a selectable session, first restart the system.

sudo reboot

If it still does not appear, verify that the COSMIC session package is installed:

apt policy cosmic-session

You can also check whether the relevant session files are present:

ls /usr/share/wayland-sessions/
ls /usr/share/xsessions/

GDM3 Does Not Appear

Reconfigure GDM3:

sudo dpkg-reconfigure gdm3

Select gdm3 when prompted.

COSMIC Installation Reports Dependency Problems

First refresh the package information:

sudo apt update

Then check for unfinished package configuration:

sudo dpkg --configure -a

After that, retry the installation only after reviewing the package-manager errors.

APT Repository Errors Appear

A third-party PPA can become unavailable or incompatible with the installed Ubuntu release. Check the configured repository:

grep -R "hepp3n/cosmic-epoch" /etc/apt/sources.list.d/ 2>/dev/null

Do not bypass repository-signature or package-integrity warnings simply to complete an installation.

Is It Safe to Install COSMIC From a PPA?

The installation method works by adding a community PPA, so it should not be presented as an official Ubuntu-supported COSMIC installation.

Ubuntu’s documentation specifically warns that third-party repositories are not checked by Ubuntu for security or reliability. Users should only add repositories they trust and should understand that doing so gives the repository owner a mechanism to distribute software to the system.

For a personal test machine, this can be a reasonable way to experiment with COSMIC. For a production workstation or managed enterprise environment, test the packages first and consider whether your organization’s software-management and security policies permit third-party PPAs.

Conclusion

Installing COSMIC Desktop on Ubuntu 24.04 LTS provides an opportunity to experience System76’s modern desktop environment without replacing Ubuntu’s existing GNOME installation.

The process is straightforward: update Ubuntu, add the COSMIC community PPA, install cosmic-session, retain GDM3, log out, and select COSMIC from the login session menu.

The most important consideration is that this method relies on a third-party PPA. It should therefore be treated differently from installing software directly from Ubuntu’s official repositories.

For users who want to experiment with COSMIC, a secondary machine or virtual machine is an excellent place to start. If you later decide COSMIC is not suitable, ppa-purge can be used to remove the PPA and restore packages where appropriate.

Technical Verification

The installation procedure in this guide is based on the referenced COSMIC installation method and has been cross-checked against Ubuntu’s current guidance for third-party repositories and System76’s documentation describing desktop-environment selection through GDM.

Last verified: October 8, 2026 • Ubuntu 24.04 LTS

Sources & References

1. Ubuntu Documentation — Add a Software Repository
2. Ubuntu Documentation — Third-Party Repository Usage
3. System76 Support — Changing Desktop Environments
4. Ubuntu Documentation — Install Software From PPAs

KS

ABOUT THE AUTHOR

Khurram Shahzad

Hybrid Cloud & Virtualization Engineer

Khurram Shahzad is a Hybrid Cloud & Virtualization Engineer focused on VMware, Microsoft Azure, AWS, Windows Server, Linux, networking, backup and disaster recovery technologies.

VMware Azure AWS Windows Server Linux Networking Backup & DR

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