During software update (though Ubuntu Software Updater) in Ubuntu 16.04, suddenly the GNU GRUB screen appeared. It could not find the linux installation anymore. Following the suggestions from [1], I used 'ls' to find out where my ubuntu kernel was located: partition (hd0,2). There were many different versions there, although more vmlinuz than initrd. Since you need to have both of the same version to boot, I used the latest version for which both files were present: vmlinuz-4.4.0-108-generic and initrd.img-4.4.0-108-generic. Using the following commands
grub> set root=(hd0,2)
grub> linux /boot/vmlinuz-4.4.0-108-generic root=/dev/sda2
grub> initrd /boot/initrd.img-4.4.0-108-generic
grub> boot
I could boot my ubuntu installation. However, after login I would get a black screen. I could login to tty1 though, so following suggestions from [2] I tried running
sudo dpkg --configure -a
but this gave an error message. Then I found various posts indicating that the 108 kernel was problematic, so instead I redid the above steps in GRUB to boot the second-latest kernel, 4.4.0-97-generic. Then also dpkg --configure -a ran without any problems and generated the missing initrd images. I updated all packages with
sudo apt-get update
sudo apt-get upgrade
Then, upon reboot, GRUB could find my installation again (now version 116)!
So that's already something. However, I still get a black screen after login, which seems to be a problem with the display manager. The software is fully up-to-date now, dpkg --configure has done all it has to do, but somehow there is an issue while starting up lightdm. Following [3], I tried to install a different display manager, gdm3, but this resulted in a similar issue: instead of a black screen after login, I was simply returned to the login screen, so I still couldn't get in. I concluded it's not a lightdm issue.
As suggested in [4], I tried purging all xserver files, lightdm and plymouth, the reinstalling all, and eventually also ubuntu-desktop. This didn't resolve the black screen, so again I ran:
sudo dpkg --configure -a
sudo apt-get update
sudo apt-get upgrade -y
which upgraded some packages. But after rebooting still no luck.
Then, after reading [5], I checked the .Xauthority file and /tmp directory and all was as it should be. I also tried logging in as a guest user, but this still lead to a black screen.
So I looked into the lightdm logs at /var/log/lightdm/:
lightdm.log doesn't show any errors
x-0.log shows a warning: The XKEYBOARD keymap compiler (XKBcomp) reports: Warning: 'Type "ONE_LEVEL" has 1 levels, but has 2 symbols. Ignoring extra symbols. Errors from xkbcomp are not fatal to the X server.
seat0-greeter.log is empty, but seat0-greeter.log.1.gz is full of warnings, the first being: Failed to register client: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files
If I manually try to startup lightdm in debug mode by typing lightdm --debug --test-mode it says "Failed to get D-Bus connection".
After login, I still get a black screen and it tells me 'System program problem detected'. I'm out of inspiration, any help would be greatly appreciated!
System information: I'm running Ubuntu 16.04 LTS on an HP laptop with Intel core i7 processor and AMD graphics card.
lspci -vk | grep -iA15 vga shows me:
VGA comptible controller: Advanced Mircro Devices, Inc. [AMD/ATI] Chelsea XT GL [FirePro M4000] (prog-if 00 [VGA controller]) ... Kernel driver in use: radeon Kernel modules: radeon
[1] After update in Ubuntu 16.04 I ended up in GNU GRUB and appear to be stuck there
[2] Ubuntu 16.04 LTS black screen after login
[3] https://wiki.ubuntu.com/LightDM#Help.2C_I_can.27t_see_my_Desktop.21
[4] http://helewix.com/howto/ubuntu-17-10-black-screen-solution/
