None of the recovery options from boot-time low-graphics mode work

[Jonathan Kamens]

In Ubuntu 16.04 x86_64, I accidentally installed the nvidia driver on a machine that actually has an intel graphics controller. This caused two different failure modes in the time I was trying to figure out what was wrong: sometimes the X server was unable to start at all, and other times it loaded both nvidia and intel drivers, successfully deduced that nvidia shouldn't have been loaded and unloaded it, and successfully displayed the lightdm login screen, but then wouldn't let me log in because the X server had failed to configure opengl properly, probably because installing the nvidia driver caused the X server to be configured to use the wrong mesa library.

This bug report is about the first failure mode mentioned above, i.e., the X server was unable to start at all on boot.

Instead, I was presented with a dialog that said "The system is running in low-graphics mode" and offered me several choices for what to do about it. I believe that this dialog was displayed by xdiagnose (version 3.8.4), which is why I'm filing this report for that package. If I'm wrong, please redirect the bug report as appropriate.

The point of this bug report is that none of the recovery options presented by the dialogs worked. In particular:

* Selecting "Try running with default graphics mode" didn't work: the screen flashed several times and then settled on a black screen showing nothing but the results of the boot-time fsck of the root filesystem. At that point, I couldn't switch VTs or anything else; the system was simply hosed and power-cycling was the only option.

* Selecting "Reconfigure graphics" (either "Use default (generic) configuration" or "Use your backed-up configuration) just flashed and returned me to the same screen asking me again which configuration to use.

* Selecting "Troubleshoot the error" and then "Edit configuration file" didn't work; I was not presented with an editor window, but rather I was simply returned to the same prompt.

* "Exit to console login" didn't work; it had the same fsck-screen failure mode described above for "Try running with default graphics mode".

I also tried booting in recovery mode and selecting failsafe graphics mode from the recovery menu. This didn't work either. See the attached screenshot for what I got when I tried that. In particular, note the "cp: cannot stat '/etc/X11/xorg.conf': No such file or directory" and "/usr/share/xdiagnose/failsafeXinit: line 117: return: zenity: numeric argument required" error messages.

[Launchpad Janitor (janitor)]

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

[Hadrien (psydk)]

I get the same error with Ubuntu 16.10. However I did not install any wrong driver. I was using AMD's amdgpu-pro proprietary drivers. I uninstalled it before upgrading my release from 16.04 to 16.10. Now I cannot start Ubuntu anymore. Starting with kernel 4.4 instead of 4.8 works.