I can confirm that on Lenovo P70 Mobile Workstation running Artful Aardvark 17.10 an upgrade to kernel 4.13.6 or higher prevented the hang on "wlp4s0: failed to remove key" (although as mentioned the error still appears in the shutdown sequence).
Workaround #2
I also found that if I went into /etc/default/grub" and removed "quiet splash", i.e. change:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
to:
GRUB_CMDLINE_LINUX_DEFAULT=""
and then run:
sudo update-grub
and reboot the hang also goes away without any need to upgrade to a higher kernel version (i.e. this fix works with the latest pushed kernel:
Workaround #1:
I can confirm that on Lenovo P70 Mobile Workstation running Artful Aardvark 17.10 an upgrade to kernel 4.13.6 or higher prevented the hang on "wlp4s0: failed to remove key" (although as mentioned the error still appears in the shutdown sequence).
Workaround #2
I also found that if I went into /etc/default/grub" and removed "quiet splash", i.e. change:
GRUB_CMDLINE_ LINUX_DEFAULT= "quiet splash"
to:
GRUB_CMDLINE_ LINUX_DEFAULT= ""
and then run:
sudo update-grub
and reboot the hang also goes away without any need to upgrade to a higher kernel version (i.e. this fix works with the latest pushed kernel:
Linux athens 4.13.0-16-generic #19-Ubuntu SMP