I recently upgraded to Kubuntu 18.04 (therefor to kernel 4.15.0-23). I can't suspend my computer anymore. However, booting on a previous kernel version still lets me suspend my computer.

This is what exactly happens when I hit on 'Suspend': System goes black, suspends (led blinking), awake by itself 1-2 seconds later.

Would you think there's an issue in the kernel? Is there any config/conflict issue ?

Thanks for your help!

Cheers,

Here are the logs:

journalctl -b | grep sleep

juil. 07 16:15:25 user-ubuntu NetworkManager[1016]: <info>  [1530972925.7995] manager: sleep: sleep requested (sleeping: no  enabled: yes)
juil. 07 16:15:25 user-ubuntu NetworkManager[1016]: <info>  [1530972925.7996] device (wlp2s0): state change: disconnected -> unmanaged (reason 'sleeping', sys-iface-state: 'managed')
juil. 07 16:15:26 user-ubuntu systemd-sleep[6022]: Suspending system...
juil. 07 16:15:31 user-ubuntu kernel: ACPI: Preparing to enter system sleep state S3
juil. 07 16:15:31 user-ubuntu kernel:  cache: parent cpu1 should not be sleeping
juil. 07 16:15:31 user-ubuntu kernel:  cache: parent cpu2 should not be sleeping
juil. 07 16:15:31 user-ubuntu kernel:  cache: parent cpu3 should not be sleeping
juil. 07 16:15:31 user-ubuntu kernel: ACPI: Waking up from system sleep state S3
juil. 07 16:15:31 user-ubuntu systemd-sleep[6022]: System resumed.
juil. 07 16:15:31 user-ubuntu systemd[1]: sleep.target: Unit not needed anymore. Stopping.
juil. 07 16:15:31 user-ubuntu systemd-logind[995]: Operation 'sleep' finished.
juil. 07 16:15:31 user-ubuntu NetworkManager[1016]: <info>  [1530972931.6845] manager: sleep: wake requested (sleeping: yes  enabled: yes)

journalctl -b | grep suspend

juil. 07 16:15:26 user-ubuntu kernel: PM: suspend entry (deep)
juil. 07 16:15:31 user-ubuntu kernel: Suspending console(s) (use no_console_suspend to debug)
juil. 07 16:15:31 user-ubuntu kernel: PM: suspend exit
juil. 07 16:15:31 user-ubuntu systemd[1]: suspend.target: Unit not needed anymore. Stopping.

Got it! My USB wifi dongle seemed to wake my system up.

Step 1: check what is allowed to wake up your system:

Open a terminal:

sudo nano /proc/acpi/wakeup

Step 2: understand the results:

Screenshot of /proc/acpi/wakeup content - step 1

The list shows what device can awake your computer. Here: EHC1 - EHC2 - XHC

Step 3: Block the device that wake up your computer:

Disable EHC1 in your terminal with:

echo EHC1 | sudo tee /proc/acpi/wakeup

Suspend your computer. If it still awakes, try

echo EHC2 | sudo tee /proc/acpi/wakeup

Note: EHC2 instead of EHC1. You can also try with XHC)

Note: above command is a kind of toggle. If you use it 2 times in a row, it will turn off EHC1, then turn it back on

Step 4: Confirm it worked

Here, it was EHC2 that woke up my computer (my USB wifi dongle). Now, it's disabled, it cannot awake my computer, and it stays suspended.

Screenshot of /proc/acpi/wakeup content - step 2

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