Replacing GDM With LightDM On Fedora

LightDM is a lighter alternative to GDM (GNOME Display Manager). If GDM is causing issues, you prefer a simpler login screen, or you’re running a lightweight desktop environment, here’s how to switch to LightDM on Fedora.

Install LightDM

sudo dnf install lightdm lightdm-gtk-greeter

The lightdm-gtk-greeter provides the graphical login screen. Other greeter options include:

lightdm-gtk-greeter — Simple, GTK-based, fast loading (recommended for most users)
lightdm-webkit2-greeter — Themeable with HTML, CSS, and JavaScript for custom login screens
lightdm-kde-greeter — KDE Plasma integration with Plasma-style branding
lightdm-another-greeter — Minimal, keyboard-driven greeter

Switch Default Display Manager

Fedora uses systemd to manage which display manager loads at boot:

# Disable GDM (current display manager)
sudo systemctl disable gdm

# Enable LightDM
sudo systemctl enable lightdm

# Switch immediately without rebooting
sudo systemctl stop gdm
sudo systemctl start lightdm

When you stop GDM, the current desktop session ends. LightDM starts with the login greeter. This change persists across reboots.

Configure LightDM

The main configuration file is /etc/lightdm/lightdm.conf:

[SeatDefaults]
greeter-session=lightdm-gtk-greeter
user-session=gnome
session-wrapper=/etc/lightdm/Xsession
allow-guest=false
xserver-command=Xorg

Key settings:

greeter-session — Which greeter to display
user-session — Default desktop session (gnome, plasma, xfce, etc.)
allow-guest — Enable or disable guest login
autologin-user — Skip login for a specific user (see below)

Customize the Greeter Appearance

Edit /etc/lightdm/lightdm-gtk-greeter.conf:

[greeter]
theme-name = Adwaita
icon-theme-name = Adwaita
background = /usr/share/backgrounds/fedora/default/standard/fedora.png
font-name = Cantarell 11
clock-format = %H:%M
show-clock = true
show-user-image = true

Set the background to any image file. For a solid color background instead:

background = #2c2c2c

Autologin Configuration

To automatically log in a user without a password prompt:

# Edit /etc/lightdm/lightdm.conf
[SeatDefaults]
autologin-user=yourusername
autologin-user-timeout=0

Add the user to the autologin group:

sudo groupadd -r autologin
sudo usermod -aG autologin yourusername

Autologin is convenient for single-user machines but reduces physical security. Anyone with access to the machine gets a full desktop session.

Switch Back to GDM

sudo systemctl disable lightdm
sudo systemctl enable gdm
sudo systemctl start gdm

GDM takes over immediately. If the switch doesn’t work cleanly, reboot.

Troubleshooting Common Issues

Black screen after switching:

# Switch to a TTY (Ctrl+Alt+F2)
# Check LightDM logs
sudo journalctl -u lightdm --since "10 minutes ago"

# Verify the greeter is installed
rpm -qa | grep lightdm
ls /usr/share/xgreeters/

Login loop (returns to login screen after entering password):

# Check for Xsession errors
cat ~/.xsession-errors

# Verify the desktop session file exists
ls /usr/share/xsessions/
ls /usr/share/wayland-sessions/

# Try a different session
# At the login screen, look for a session dropdown (usually near username)

LightDM doesn’t start after reboot:

# Verify the service is enabled
systemctl is-enabled lightdm

# Ensure graphical target is set
sudo systemctl set-default graphical.target

# Manually start if needed
sudo systemctl start lightdm

LightDM vs GDM Comparison

Choose LightDM when:

Running lightweight desktops (Xfce, LXQt, MATE, i3)
You need custom login screen theming
GDM has bugs or conflicts with your setup
Running on older hardware where every MB of RAM counts

Choose GDM when:

Running GNOME desktop (tighter integration)
You need Wayland support out of the box
Accessibility features are important
You use GNOME’s screen recording, remote login, or multi-seat features

GDM and GNOME are developed together, so GDM has better support for GNOME-specific features. LightDM is more flexible and desktop-agnostic.

Quick Reference

sudo dnf install lightdm lightdm-gtk-greeter — Install
sudo systemctl enable lightdm — Set as default
/etc/lightdm/lightdm.conf — Main config
/etc/lightdm/lightdm-gtk-greeter.conf — Greeter appearance
sudo systemctl disable lightdm && sudo systemctl enable gdm — Switch back

Replacing GDM with LightDM on Fedora