I have this problem again, however this time I updated a bunch of packages and rebooted straight away and now have the problem after boot.
$ sudo systemctl virtualbox restart Unknown operation virtualbox. $ ps aux | grep plymouth root 735 0.0 0.3 139000 28576 ? S 08:37 0:00 @sbin/plymouthd --mode=boot --pid-file=/run/plymouth/pid --attach-to-session root 1029 0.0 0.0 12936 1124 ? Ss 08:37 0:00 /bin/plymouth --wait root 1290 0.0 0.0 12936 1076 ? S 08:37 0:00 /bin/plymouth quit root 1376 0.0 0.0 12936 1128 ? S 08:37 0:00 plymouth --ping root 1377 0.0 0.0 12936 1016 ? S 08:37 0:00 plymouth --ping root 1381 0.0 0.0 12936 1040 ? S 08:37 0:00 plymouth --ping Plymouth is waiting, quiting, pinging. $ sudo service virtualbox restart is the only thing that works, but you have to kill the latest plymouth --ping it spawns in order for the service to start. Starting the virtualbox service on boot can sometimes delay the boot up process due to this bug. ** Changed in: virtualbox (Ubuntu) Status: Invalid => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1722745 Title: Virtualbox service fails to start due to hanging plymouth --ping response To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/virtualbox/+bug/1722745/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs