Recently, after updating and upgrading my RHEL 9 system using dnf, I encountered an issue where the system froze at "Starting GNOME Display Manager (GDM)."

This guide outlines the troubleshooting steps I followed to successfully resolve it.

Table of Contents

What is GNOME Display Manager (GDM)?

The GNOME Display Manager (GDM) is a graphical login manager for Linux systems that use the GNOME desktop environment.
Its key functions include:

  • User Authentication: Provides a secure graphical interface for login.

  • Session Management: Starts and manages user sessions.

  • Customizable Interface: Offers a user-friendly login screen.

  • Display Server Support: Works with both X11 and Wayland display servers.

In simple terms, GDM acts as a bridge between the user and the GNOME desktop environment.

Common Causes of GDM Hanging Issues

The "Starting GNOME Display Manager" hang can occur due to:

  • Package conflicts or incomplete updates.

  • Graphics driver issues.

  • Misconfigured system services.

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Troubleshooting Steps

1. Switch to a TTY Console

When the system is stuck:

  • Press Ctrl + Alt + F2 (or F3/F4, depending on the system) to access a text-based terminal.

  • Log in with your credentials.

2. Restart GDM Service

In the terminal, restart the GDM service:

sudo systemctl restart gdm

Sometimes, a simple restart can fix a stuck GDM.

3. Review GDM Logs for Errors

If restarting didn’t work, check the system logs:

journalctl -xeu gdm

Look for specific error messages that can guide your next steps.

4. Reset GNOME Desktop Settings

If there are misconfigurations in the GNOME settings, resetting them might help:

dconf reset -f /org/gnome/

Then, restart GDM:

sudo systemctl restart gdm

5. Boot into Multi-User Mode for Deeper Troubleshooting

If the problem persists:

Reboot and access the GRUB menu (press Esc or Shift during boot)

Edit the boot entry and add:

systemd.unit=multi-user.target

Press Ctrl + X to boot

This boots into a command-line environment (without GUI), allowing safer troubleshooting.

GNOME Session Shows "Unsupported Session Type"

Error:

Window Manager Warning: Unsupported session type

How to Fix:

  • Check the session type: 
echo $XDG_SESSION_TYPE

If it shows tty instead of x11 or wayland, your graphical session isn't active.

  • Start GNOME manually: 
startx
  • Set the system to boot into graphical mode by default:

Check the default target:

systemctl get-default

If it returns multi-user.target, change it:

sudo systemctl set-default graphical.target
reboot

Conclusion

If you ever encounter a GNOME Display Manager issue in RHEL 9, these steps should guide you to a solution.

Always check system logs, verify configuration settings, and ensure your graphics drivers are up-to-date.

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