tedaste, using the default Ubuntu kernel (not 3rd party), could you please utilize your WORKAROUNDs, boot into a working system, and then execute the following via a terminal as it will attach necessary debugging information: apport-collect 1525615
** Tags added: xenial ** Description changed: - With a 27in 5k ( new as of two weeks ago) I'm unable to boot the kernel - without parameter "acpi=off:", it also needs "nomodeset" into order to - get a working system. + With a 27in 5k ( new as of two weeks ago) I'm unable to boot. The + applies to both the live installer and a system installed on disk. I + just get a blank screen. It gives a blank screen event if the "quiet" is + removed from the kernel parameters. The system has a 250G SSD. I'm using + the Kubutu live installer for Wily off a USB stick. - The applies to both the live installer and a system installed on disk. - With out the parameters I just get a blank screen. It gives a blank - screen event if the "quiet" is removed from the kernel parameters. + WORKAROUND: Use kernel parameters: + acpi=off nomodeset - The system has a 250G SSD. - - I'm using the Kubutu live installer for Wily off a USB stick. - --- + --- ApportVersion: 2.19.1-0ubuntu5 Architecture: amd64 CurrentDesktop: KDE DistroRelease: Ubuntu 15.10 InstallationDate: Installed on 2015-12-08 (9 days ago) InstallationMedia: Kubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021) Package: linux (not installed) Tags: wily Uname: Linux 4.4.0-040400rc5-generic x86_64 UnreportableReason: The running kernel is not an Ubuntu kernel UpgradeStatus: No upgrade log present (probably fresh install) UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo _MarkForUpload: True -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1525615 Title: Ubuntu not booting on iMac 5K with ACPI enabled To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1525615/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs