Ubuntu 26.04 LTS – login loop occurs when switching between Wayland and Xorg

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

Administrators observe: Ubuntu 26.04 LTS – login loop occurs when switching between Wayland and Xorg. Users cannot reach stable desktop sessions.

Environment & Reproduction

Issue appears after display driver changes, session config edits, or permissions drift in user runtime files.

# Baseline context
lsb_release -a
systemctl status gdm3 --no-pager
ls -la ~/.Xauthority ~/.config 2>/dev/null
sudo journalctl -u gdm3 -n 120 --no-pager
sudo journalctl -b -p err --no-pager | tail -n 120

Root Cause Analysis

Session startup can fail due to incompatible graphics path, stale authority files, or broken user session configs.

Quick Triage

Validate gdm3 health and clear stale user auth/session files.

# Quick triage
loginctl
sudo systemctl restart gdm3
mv ~/.Xauthority ~/.Xauthority.bak 2>/dev/null || true
mv ~/.cache ~/.cache.bak 2>/dev/null || true

Step-by-Step Diagnosis

Inspect display manager logs and per-user journal entries for session failures.

# Detailed diagnosis
sudo journalctl -u gdm3 --since '2 hours ago' --no-pager
journalctl --user -b --no-pager | tail -n 200
cat /etc/gdm3/custom.conf

Solution – Primary Fix

Set a known-good session mode and reset broken user session artifacts.

# Primary fix
sudo sed -i 's/^#WaylandEnable=false/WaylandEnable=false/' /etc/gdm3/custom.conf
rm -f ~/.Xauthority ~/.ICEauthority
rm -rf ~/.cache/gdm-session-worker
sudo systemctl restart gdm3

Solution – Alternative Approaches

Switch display manager to isolate whether issue is gdm-specific.

# Alternative
sudo apt-get install -y lightdm
sudo dpkg-reconfigure lightdm
sudo reboot

Verification & Acceptance Criteria

User login succeeds repeatedly with expected desktop session type.

# Verify
loginctl
echo $XDG_SESSION_TYPE
systemctl is-active gdm3

Rollback Plan

Restore original display manager settings and user config backups if needed.

# Rollback
sudo sed -i 's/^WaylandEnable=false/#WaylandEnable=false/' /etc/gdm3/custom.conf
mv ~/.Xauthority.bak ~/.Xauthority 2>/dev/null || true
sudo systemctl restart gdm3

Prevention & Hardening

Validate graphics/session changes in non-production desktops before broad rollout.

# Hardening
sudo apt-get install -y needrestart
sudo journalctl -u gdm3 --since '7 days ago' --no-pager | grep -Ei 'fail|error' || true

Related Errors & Cross-Refs

Related patterns include gdm greeter restart loops and cannot start GNOME session.

Related tutorial: View the step-by-step tutorial for Ubuntu 26.04 LTS.

View all Ubuntu 26.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Ubuntu desktop session management and gdm3 administration documentation.