Public bug reported:

# Mutter Bug Report

**File at:** https://bugs.launchpad.net/ubuntu/+source/mutter/+filebug

**Summary:** Drag and drop from Nautilus to Firefox crashes with Wayland
protocol error on mutter 49

---

## Description

### Summary

Dragging files from Nautilus to Firefox on native Wayland intermittently
fails and crashes Firefox with a Wayland protocol error. Behavior is
random across attempts: sometimes nothing happens (drop silently
ignored), sometimes it works, sometimes Firefox crashes.

### Steps to reproduce

1. Open Nautilus and Firefox (both native Wayland)
2. Drag a file from Nautilus toward a Firefox window (e.g. Gmail compose, 
Google Drive upload, or any `<input type="file">`)
3. Repeat 3-5 times

### Expected behavior

File is accepted by the drop target every time.

### Actual behavior

Randomly one of:
- Nothing happens (drop silently cancelled)
- Drop works correctly
- Firefox crashes with SIGSEGV

Approximately 1 in 5 attempts causes a crash. The intermittent silent
failures match the pattern described in GNOME/mutter#1658 where
`wl_data_device::start_drag()` is silently cancelled.

### Crash details

From Firefox crash report:
```
MozCrashReason: (ubuntu:gnome) unknown object (4278190083), message error(ous)
GraphicsCriticalError: [GFX1-]: (ubuntu:gnome) Wayland protocol error: unknown 
object (4278190083), message error(ous)
```

Crash is SIGSEGV / SEGV_MAPERR at address 0x0 on the main thread. Stack
trace goes through `libwayland-client.so.0` -> `libgdk-3.so.0` ->
`libxul.so`, indicating mutter handed Firefox a stale/destroyed Wayland
proxy object during the DnD operation.

### Environment

- **OS:** Ubuntu 25.10 (Questing Quetzal)
- **Kernel:** 6.17.0-19-generic
- **mutter:** 49.0-2ubuntu5.3
- **gnome-shell:** 49.0-1ubuntu1.2
- **Nautilus:** 49.0-1ubuntu2
- **Firefox:** 148.0.2 (deb from mozillateam PPA, not snap)
- **Session:** Wayland (MOZ_ENABLE_WAYLAND=1)
- **GPU:** Intel Iris Xe (RPL-P) + NVIDIA RTX A1000 (mesa/iris 25.2.8)
- **Display:** 2560x1600 @ 133% scaling

### Possibly related

- GNOME/mutter#1658 — Firefox/Wayland: Drag and Drop fails (same `start_drag` 
silent cancellation pattern)
- GNOME/mutter#740 — Firefox - start_drag fails in mutter
- GNOME/mutter#1057 — Gnome Shell crashes when Firefox gets dragged over a 
wayland app

The fix backported to mutter 46.2 for Ubuntu 24.04 may not fully cover
the code paths in mutter 49.

** Affects: firefox (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: questing

-- 
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https://bugs.launchpad.net/bugs/2144616

Title:
  Drag and drop from Nautilus to Firefox crashes with Wayland protocol
  error on mutter 49

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