I tested with xfce4-session 4.13 and virtualbox 6.0, and I can confirm this bug. The process does not end immediately though.
VBoxSVC.log: 00:00:25.454822 main VirtualBox: object deletion starts 00:00:25.803381 Watcher ERROR [COM]: aRC=E_ACCESSDENIED (0x80070005) aIID={d0a0163f-e254-4e5b-a1f2-011cf991c38d} aComponent={VirtualBoxWrap} aText={The object is not ready}, preserve=false aResultDetail=0 00:00:30.467997 main {00007f6e30016820} HostPowerServiceLinux::~HostPowerServiceLinux: RTThreadWait() for 5000 ms failed with VERR_TIMEOUT 00:00:30.468881 main VirtualBox: object deleted -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1504186 Title: virtualbox interferes with shutdown,restart or logout To manage notifications about this bug go to: https://bugs.launchpad.net/xfce4-session/+bug/1504186/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs