You have your shiny new Ubuntu system up and running and everything seems to be working fine. You then go to shutdown for the first time and the system hangs, unable to complete the shutdown sequence. Is this fatal to your Ubuntu install? No, it's not. However, it does mean that one of your system services is having a problem when trying to properly terminate itself. You can simply power your system off and the next time you boot, chances are everything will be fine ... until the next time you attempt a full shutdown. You could, in theory, continue to do a hard shutdown of your system for quite some time, but we're Linux users! Lets investigate and fix the problem instead of ignoring it.
The first thing you will want to look at when experiencing shutdown problems is ACPI (Advanced Configuration and Power Interface). This, in my experience, is the most common culprit when it comes to Linux shutdown problems. When troubleshooting ACPI, please follow the steps below:
- Try booting with the "acpi=off" kernel parameter: This will disable ACPI support. If the error is the same with acpi enabled and disabled, you are probably not having an ACPI issue. If that is the case, please see the section of this article titled "Other Possible Solutions".
- If "acpi=off" allows the system to boot, you will need to isolate the ACPI issue by trying each of the following boot parameters.
- Try booting with "acpi=ht": This disables all of ACPI except just enough to enable Hyper Threading. If acpi=off works and acpi=ht fails, then the issue is in the ACPI table parsing code itself, or perhaps the SMP code.
- Try booting with "pci=noacpi": This disables ACPI for IRQ routing and PCI scanning.
- Try booting with "acpi=noirq": This disables ACPI for IRQ routing.
- Try booting with "pnpacpi=off": This disables the ACPI component of the Linux Plug and Play code.
- Try booting with "noapic": This disables the IO-APIC for IRQ routing or PCI scanning.
- Try booting with "nolapic": This disables the local APIC.
With any luck one of these extra boot parameters has solved your problem with Ubuntu hanging on shutdown. If not, ACPI was not the problem and we'll need to look at other possible solutions. Please skip ahead to "Other Possible Solutions". If one or more of these boot parameters solved your problem with Ubuntu hanging on shutdown consult the next section on how to make the changes permanent.