After updating nvidia-common to 1:0.2.91.7, nvidia drivers are no longer in use

[Eric Munson]

1) The release of Ubuntu you are using, via 'lsb_release -rd' or System -> About Ubuntu
Description: Ubuntu 14.04.1 LTS
Release: 14.04

2) The version of the package you are using, via 'apt-cache policy pkgname' or by checking in Software Center
nvidia-common:
  Installed: 1:0.2.91.7
  Candidate: 1:0.2.91.7
  Version table:
 *** 1:0.2.91.7 0
        500 http://my-mirror/archive-ubuntu/ubuntu/ trusty-updates/universe amd64 Packages
        100 /var/lib/dpkg/status
     1:0.2.91.4 0
        500 http://my-mirror/archive-ubuntu/ubuntu/ trusty/universe amd64 Packages

3) What you expected to happen
nVidia binary drivers are used

4) What happened instead
nouveau Xorg driver is used, but the nVidia kernel module is loaded.

I updated this package yesterday but did not reboot. When I started my machine this morning I could only boot into the terminal. Xorg.0.log said that the nvidia module did no exist. After purging the nvidia driver and reinstalling, I can now start the machine and get into X, but the nouveau driver X driver is in use.

ldmod shows the nvidia driver loaded:
...
ppdev 17671 0
nvidia 10675249 0
snd_hda_codec_hdmi 46368 1
...

But Xorg.0.log says the Xorg driver could not be found:
[ 9.730] (II) LoadModule: "nvidia"
[ 9.731] (WW) Warning, couldn't open module nvidia
[ 9.731] (II) UnloadModule: "nvidia"
[ 9.731] (II) Unloading nvidia
[ 9.731] (EE) Failed to load module "nvidia" (module does not exist, 0)

The Driver Manager says that I am using the nvidia driver version 331.38, but update-alternatives has the MESA ld.so.conf selected:

$ sudo update-alternatives --config x86_64-linux-gnu_gl_conf
There are 3 choices for the alternative x86_64-linux-gnu_gl_conf (providing /etc/ld.so.conf.d/x86_64-linux-gnu_GL.conf).

  Selection Path Priority Status
------------------------------------------------------------
  0 /usr/lib/nvidia-331/ld.so.conf 8604 auto mode
  1 /usr/lib/nvidia-331-prime/ld.so.conf 8603 manual mode
  2 /usr/lib/nvidia-331/ld.so.conf 8604 manual mode
* 3 /usr/lib/x86_64-linux-gnu/mesa/ld.so.conf 500 manual mode

If I select 0 and log out and back in, the nvidia driver is in use, but I cannot start Steam. This select also does not survive a reboot.

[Launchpad Janitor (janitor)]

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

[Trafex (trafex)]

I think I've the same problem.
Updated yesterday, started my computer this morning and after the boot screen I'm only seeing a blinking cursor on a black screen.
Tought it had something todo with lightdm, but nothing I tried fixed it.

After that I've removed all nvidia packages: sudo apt-get purge nvidia-*
Rebooted, and choose the nvidia-331-updates driver I was using before (via Additional Drivers).
This gave the blinking cursor again. So I've tried the other drivers (nvidia-331, nvidia-304, nvidia-304-updates), but none of these installed correctly. After every reboot I got the failsafe mode from Xorg.

I've also tried to downgrade nvidia-common to 1:0.2.91.4, but this again caused to fallback in the failsafe mode.

Ps. I'm also missing the nvidia-xconfig command, used it a few days ago.

[Trafex (trafex)]

I've fixed it by not only downgrading nvidia-common to 1:0.2.91.4 but also ubuntu-drivers-common to 1:0.2.91.4.
After that I've reinstalled the nvidia-331-updates and everything works again.