Workaround Xauthority error using VirtualBox on Wayland

Wayland desktop on Ubuntu 17.10 after install/upgrade a VirtualBox Extension Pack may get a “can’t find Xauthority” popup error. The fix is to revert to X11 as recommended by Ubuntu.

  1. logout
  2. on login screen select X11 login
  3. install the VirtualBox Expansion Pack
  4. if you desire, logout and switch back to the default login (with Wayland). VirtualBox will work in Wayland.

Ubuntu 18.04 defaults to X11 once again.