Bottom panel disappears after cinnamon --replace; session becomes difficult to recover

[teriodore]

Distribution

Linux Mint 21.3 Virginia

Package version

Cinnamon 6.0.4

Graphics hardware in use

NVIDIA 470.256.02

Frequency

Always

Bug description

After running cinnamon --replace, the Cinnamon bottom panel disappeared and the session became difficult to recover. Normal recovery shortcuts did not work, and I had to use Magic SysRq to regain control and then reboot normally.

Steps to reproduce

1. Start a normal Linux Mint Cinnamon session.
2. Open a terminal.
3. Run:

cinnamon --replace

4. Wait for Cinnamon to restart.
5. Observe the bottom panel / taskbar area.
6. Try normal recovery methods if the panel does not return.

Expected behavior

cinnamon --replace should restart Cinnamon cleanly. The bottom panel should return, and the session should remain controllable. If something fails, normal recovery methods such as Alt+F2, opening a terminal, Ctrl+Alt+Delete, or switching to a TTY should still work.

Additional information

Actual:
The bottom panel disappeared and did not return. The session became difficult to control.

The following recovery methods did not work:

Alt+F2
Ctrl+Alt+T
Ctrl+Alt+Delete
TTY switching with Ctrl+Alt+F3

I eventually used Magic SysRq. After pressing Alt+SysRq and then R/E, the session recovered/reset enough for me to reboot normally.

Environment:

OS: Linux Mint 21.3 Virginia
Cinnamon: 6.0.4
Session: X11
Kernel: 5.15.0-179-generic
GPU: NVIDIA GeForce GTX 760
NVIDIA driver: 470.256.02
Xorg NVIDIA package: xserver-xorg-video-nvidia-470 470.256.02-0ubuntu0.22.04.1
Architecture: amd64
Monitors: dual monitor setup, 2560x1600 + 2560x1440

Additional terminal output seen around the failed restart:

Gjs-Message: JS LOG: [LookingGlass/info] Cinnamon took 1234 ms to start
GLib-GObject-WARNING **: value "-32,000000" of type 'gfloat' is invalid or out of range for property 'margin-bottom' of type 'gfloat'
Gjs-Message: JS LOG: [LookingGlass/info] GPU offload supported: false
Window manager warning: calendar-open-13 - Overwriting existing binding of keysym 63 with keysym 63 (keycode 36).
Gjs-Message: JS LOG: Enabling WindowAttentionHandler

Notes:
I understand that cinnamon --replace is often used as a troubleshooting/recovery command. In this case it made the session worse: the panel disappeared and normal keyboard recovery paths failed.

[teriodore]

Update:

I retested cinnamon --replace later after making backups and preparing recovery steps. On that later attempt, Cinnamon restarted successfully and the bottom panel returned normally.

So this does not appear to reproduce every time. The earlier failure was still real — the panel disappeared, normal recovery shortcuts did not work, and I had to use Magic SysRq to regain control — but the issue may be intermittent or dependent on session state.

Updated interpretation:

• cinnamon --replace can work normally on this system.
• It previously failed in a way that left the session difficult to recover.
• I would no longer describe the frequency as “Always”; “intermittent” or “state-dependent” is more accurate.
• I am treating cinnamon --replace as a controlled troubleshooting step now: save work first and have recovery steps ready.