Unity 8 Desktop Preview does not work in the guest session

[Stephen M. Webb]

Selecting the Unity 8 session for the Guest Session in lightdm brings up a black screen (with a movable mouse cursor). There is no interaction available and requires a reboot to exit.

The file /tmp/guest-23eDg5/.cache/upstart/unity8-mir.log contains the following.

()
terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<std::runtime_error> >'
  what(): Nested Mir Platform Connection Error: connect: Permission denied

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: unity8-desktop-session-mir 1.0.10+14.04.20140402-0ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9
Uname: Linux 3.13.0-24-generic x86_64
ApportVersion: 2.14.1-0ubuntu2
Architecture: amd64
Date: Mon Apr 14 12:54:22 2014
InstallationDate: Installed on 2013-05-09 (340 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
SourcePackage: unity8-desktop-session
UpgradeStatus: Upgraded to trusty on 2013-10-31 (164 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.