I am encountering a persistent shutdown issue that seems to be specific to Ubuntu, and I would like help diagnosing it.
System Information:
Hardware: Lenovo ThinkPad P50s
Architecture: x86_64
Boot mode: UEFI
Storage: Internal SSD (issue also occurs with no external devices connected)
Affected Ubuntu Versions:
Ubuntu 24.04 LTS
Ubuntu 25.04
This issue occurs on both versions.
Other Operating Systems (for comparison):
Windows (same machine) → shuts down normally
Kali Linux (same machine) → shuts down normally
This suggests the problem is not hardware-related, but likely related to Ubuntu-specific kernel, systemd, ACPI, or power management behavior.
Problem Description:
When selecting Shut Down in Ubuntu
The shutdown process starts
The screen may go black or stay on a shutdown screen, however the system never fully powers off.
Power LED remains on, and sometimes fans keep running. The only way to turn the machine off is by holding down the power button.
Steps to reproduce:
Boot into Ubuntu (24.04 or 25.04).
Use the system normally (or even stay idle).
Click “Shut Down” from the system menu.
The system hangs and does not power off.
What works:
Reboot usually works correctly.
Shutdown works normally on Windows and Kali Linux.
What I have tried:
Waiting several minutes during shutdown
Disconnecting all USB / external drives
Fully updating the system
Checking dmesg and journalctl for errors
Expected Behavior:
The system should power off completely after shutdown.
Actual Behavior:
Shutdown hangs and requires a forced power-off.
Suspicions / Questions:
Possible ACPI or power-off (poweroff.target) issue
Ubuntu-specific kernel or systemd configuration
Missing or incompatible kernel parameters for ThinkPad P50s
I would appreciate advice on:
What logs or debug options to collect
Kernel parameters (e.g. acpi=, reboot=) worth testing
Whether this is a known issue with recent Ubuntu kernels