GDM Login Loop on Desktop

📖 ~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

User authenticates, screen flashes, then returns to GDM login repeatedly, blocking desktop access.

Environment & Reproduction

Common after graphics driver updates, Wayland/Xorg mismatch, or corrupted user session files.

Root Cause Analysis

Display manager starts then crashes session due to GPU driver incompatibility, permissions, or shell extension issues.

Quick Triage

Switch to TTY (`Ctrl+Alt+F3`) for stable command-line recovery.

Step-by-Step Diagnosis

Inspect `sudo journalctl -u gdm -b`, verify GPU modules (`lsmod`), and check home ownership/space with `df -h` and `ls -ld ~`.

Solution – Primary Fix

Reinstall/align GPU driver packages, disable problematic shell extensions, and test toggling Wayland in GDM config.

Solution – Alternative Approaches

Create a new test user profile to isolate per-user corruption, or use lightdm temporarily for confirmation.

Verification & Acceptance Criteria

Desktop session loads and persists through logout/login and reboot without loop recurrence.

Rollback Plan

Revert to prior graphics driver version and restore previous display manager settings.

Prevention & Hardening

Stage GPU updates, keep fallback kernel, and document known-good display stack versions.

Related Errors & Cross-Refs

`gnome-shell` segfaults, `gdm-wayland-session` failures, and Xorg permission warnings.

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 troubleshooting and GNOME/GDM upstream docs.