I get the same error when waking up from suspend. Have two monitors (HDMI, DVI) connected through Lenovo docking station.
$ lsb_release -rd Description: Ubuntu 14.04.2 LTS Release: 14.04 $ uname -a Linux raccoon 3.19.0-20-generic #20~14.04.1-Ubuntu SMP Fri May 29 19:33:06 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux $ apt-cache policy xserver-xorg-video-intel xserver-xorg-video-intel: Installed: 2:2.99.917+git20150528.fb1643f0-0ubuntu0sarvatt~trusty Candidate: 2:2.99.917+git20150528.fb1643f0-0ubuntu0sarvatt~trusty Version table: *** 2:2.99.917+git20150528.fb1643f0-0ubuntu0sarvatt~trusty 0 500 http://ppa.launchpad.net/xorg-edgers/ppa/ubuntu/ trusty/main amd64 Packages 100 /var/lib/dpkg/status 2:2.99.910-0ubuntu1.6 0 500 http://at.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages 2:2.99.910-0ubuntu1 0 500 http://at.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-video-intel in Ubuntu. https://bugs.launchpad.net/bugs/1465506 Title: plane A assertion failure (expected on, current off) on Intel NUC 5i5RYH To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1465506/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp