---
service: xorg
symptoms: xorg black screen, display manager loop, no screens found, failed to start X server, GPU driver error, xrandr missing outputs, login screen not appearing
tags: xorg, x11, display, gpu, drm, xrandr, gdm, sddm, lightdm
---

## Symptoms

- Black screen after graphical boot
- Display manager loops back to login
- `no screens found` in Xorg log
- External monitors are missing or not detected
- X server fails after a driver update
- `startx` exits immediately with display or device errors

## Diagnostics

### Check display manager and Xorg service path

```
systemctl status display-manager
systemctl status gdm
systemctl status sddm
systemctl status lightdm
```

If the display manager is failing, inspect its logs before focusing on Xorg itself.

### Check Xorg logs

```
find /var/log -name 'Xorg*.log' -o -name 'Xorg.*.log'
grep -E '\(EE\)|\(WW\)' /var/log/Xorg.0.log
journalctl -b | grep -iE 'xorg|gdm|sddm|lightdm'
ls -la ~/.local/share/xorg/
```

Look for: `no screens found`, GPU module load failures, and permission/device access errors.

On rootless Xorg, logs are often under `~/.local/share/xorg/Xorg.0.log` instead of `/var/log/`.

### Check DRM and GPU driver state

```
lspci -k | grep -A3 -E 'VGA|3D|Display'
lsmod | grep -E 'nouveau|nvidia|amdgpu|i915'
dmesg | grep -iE 'drm|gpu|nvidia|amdgpu|i915'
```

Driver mismatches after kernel updates are a common cause of X startup failures.

### Check monitor detection and permissions

```
loginctl session-status
xrandr --query
ls -la /dev/dri/
ps -o user= -C Xorg
```

If `/dev/dri/*` permissions or seat assignment are wrong, X may fail to access the GPU.

### Check X configuration files

```
find /etc/X11 -maxdepth 3 -type f
cat /etc/X11/xorg.conf
cat /etc/X11/xorg.conf.d/*.conf
ls -la ~/.xinitrc ~/.xserverrc
```

Custom `Device`, `Monitor`, or `Screen` sections often break auto-detection.

An empty or broken `.xinitrc` can produce a black screen even when the X server itself started correctly.

## Remediation

**Bad static Xorg config:**
Move custom config aside and let auto-detection work unless the hardware truly needs manual config.

**Driver mismatch after update:**
Reinstall the GPU driver package matching the running kernel and reboot or restart the display manager.

**`no screens found`:**
Check whether the correct DRM module loaded and whether the display manager is running on the expected seat.

**Display manager loop:**
Correlate Xorg errors with PAM/auth logs; some loops are session startup failures, not graphics failures.

**Framebuffer mode failure:**
If X falls back to `fbdev` and errors with framebuffer/bus ID messages, remove the generic `fbdev` driver package and let Xorg use the proper modesetting or vendor driver.

**`SocketCreateListener() failed`:**
Check for stale sockets in `/tmp/.X11-unix`, especially after previous root-run Xorg sessions.