Sorry, I didn't want to make mess. I think it has been in the update of the *2016-02-08*, I remember in that update there was the linux-image-4.4. This seems correct as in the following day I intalled xfce to log in and send the bug report. This is the dpkg log of those days. I'm sorry that's still a massive update..
** Attachment added: "log containing the updates after which the regression begun" https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1543745/+attachment/4572675/+files/dpkg.log.1 -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1543745 Title: Xorg crash prevents login Status in xorg package in Ubuntu: Incomplete Bug description: After a recent update, it's no more possible to log in to Ubuntu 16.04 trough lightdm with Unity. WORKAROUND: sudo apt purge nvidia* ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: xorg 1:7.7+13ubuntu1 ProcVersionSignature: Ubuntu 4.3.0-7.18-generic 4.3.3 Uname: Linux 4.3.0-7-generic x86_64 .tmp.unity.support.test.0: ApportVersion: 2.19.4-0ubuntu2 Architecture: amd64 CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins' CompositorRunning: compiz CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0' CompositorUnredirectFSW: true CurrentDesktop: Unity Date: Tue Feb 9 20:11:26 2016 DistUpgraded: Fresh install DistroCodename: xenial DistroVariant: ubuntu DkmsStatus: bbswitch, 0.8, 4.3.0-5-generic, x86_64: installed bbswitch, 0.8, 4.3.0-7-generic, x86_64: installed bbswitch, 0.8, 4.4.0-2-generic, x86_64: installed psmouse-focaltech, 0.1, 3.19.0-18-generic, x86_64: installed psmouse-focaltech, 0.1, 3.19.0-20-generic, x86_64: installed ExtraDebuggingInterest: Yes GraphicsCard: Intel Corporation 4th Gen Core Processor Integrated Graphics Controller [8086:0416] (rev 06) (prog-if 00 [VGA controller]) Subsystem: ASUSTeK Computer Inc. 4th Gen Core Processor Integrated Graphics Controller [1043:178d] InstallationDate: Installed on 2015-03-21 (325 days ago) InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Alpha amd64 (20150321) Lsusb: Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 003: ID 0bda:57b4 Realtek Semiconductor Corp. Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub MachineType: ASUSTeK COMPUTER INC. X550JK ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.3.0-7-generic.efi.signed root=UUID=3eab3ace-7b67-4e6a-aea7-d31b73cc4819 ro quiet splash acpi_osi= SourcePackage: xorg Symptom: display UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 10/08/2014 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: X550JK.303 dmi.board.asset.tag: ATN12345678901234567 dmi.board.name: X550JK dmi.board.vendor: ASUSTeK COMPUTER INC. dmi.board.version: 1.0 dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 10 dmi.chassis.vendor: ASUSTeK COMPUTER INC. dmi.chassis.version: 1.0 dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrX550JK.303:bd10/08/2014:svnASUSTeKCOMPUTERINC.:pnX550JK:pvr1.0:rvnASUSTeKCOMPUTERINC.:rnX550JK:rvr1.0:cvnASUSTeKCOMPUTERINC.:ct10:cvr1.0: dmi.product.name: X550JK dmi.product.version: 1.0 dmi.sys.vendor: ASUSTeK COMPUTER INC. version.compiz: compiz 1:0.9.12.2+16.04.20151211-0ubuntu1 version.ia32-libs: ia32-libs N/A version.libdrm2: libdrm2 2.4.66-2 version.libgl1-mesa-dri: libgl1-mesa-dri 11.1.1-1ubuntu2 version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A version.libgl1-mesa-glx: libgl1-mesa-glx 11.1.1-1ubuntu2 version.xserver-xorg-core: xserver-xorg-core 2:1.17.3-2ubuntu2 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.2-1ubuntu1 version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.6.1-1 version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20160127-1ubuntu1 version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.12-1 xserver.bootTime: Tue Feb 9 19:54:16 2016 xserver.configfile: default xserver.errors: systemd-logind: failed to get session: PID 926 does not belong to any known session xserver.logfile: /var/log/Xorg.0.log xserver.outputs: product id 1117 vendor LGD xserver.version: 2:1.17.3-2ubuntu2 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1543745/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp