Ubuntu – Problem booting after updating from Ubuntu 14.10 to 15.04


I just updated my laptop from Ubuntu 14.10 to Ubuntu 15.04. Now on a restart it fails to make it to the login prompt. The system looks to be in a cycle of failure and I see the message repeatedly

[ OK ] Started Light Display Manager.
[ OK ] Started ACPI event daemon.
       Starting ACPI event daemon...
       Starting Network Manager Script Dispatcher Service....
[ OK ] Started Network Manager Script Dispatcher Service.

The contents of /var/log/Xorg.0.log show a segfault. Sorry I can't copy the backtrace now, but the chain goes

Segmentation fault at address 0x41

I'm on a Dell Precision m3800. Since the nVidia driver is implicated in the stack trace, I'll start with swapping that out.

Any suggestions for my next steps to try to fix this?


Best Answer

I was able to fix this after reading the bug report @Mondane mentioned and several other troubleshooting articles on recovery mode.

  1. Boot into GRUB menu (pressing shift while starting).
  2. Choose recovery mode.
  3. Enable networking.
  4. Drop to root shell prompt.
  5. ifconfig eth0 and dhclient eth0 to get
  6. (Probably unnecessary) I had a some networking issues that were probably unrelated to this (undetermined so far) so I had to edit /etc/resolv.conf to include Google DNS and
  7. See what drivers are available for the nvidia hardware: ubuntu-drivers devices
  8. Install the recommended: apt-get install nvidia-346
  9. Reboot normally.
  10. Go to sleep.

Some resources I found useful:

For reasons I haven't yet determined, my networking was really messed up. I had to unplug and replub the USB-to-ethernet, run dhclient, then apt-get install nvidia-346 to get about 5% of the update before networking failed. This might be a hardware issue and totally unrelated, but it made troubleshooting and fixing this problem especially difficult.

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