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I upgraded to Ubuntu 15.04 which was just released. After reboot, I get as far as the login screen but it only appears for a second, then it goes to an infinite loop of screen flickering. How could I fix it?

Here is a video of what I'm seeing: https://youtu.be/NCtCw267v8Y

(The tag "Nvidia" is added to this question as that is, or at least was, my graphics driver.)

Note that switching to upstart does not fix this, nor am I able to enter the command line with ctrl+alt+f2.

Update: when I boot with recovery mode, /var/log/Xorg.0.log is empty, and I can at least enter my password (which in normal mode is impossible) but then it starts the same flickering, see this second video recording: https://youtu.be/AdOqBKPnUKA

Valid workaround: go to recovery mode, open a root shell, get list of relevant packages with dpkg -l | grep -i nvidia and remove them all with apt-get remove --purge [package] (for me, they were versions 340 and 331 while the one nvidia itself recommends me - 350 - is not in any ubuntu package)

Solution: upgrade your kernel like this.

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  • Possible duplicate askubuntu.com/questions/613009/…
    – Velkan
    Apr 24, 2015 at 21:34
  • It is definitely not a duplicate of that one, but if you have an answer, would be happy to hear it.
    – Gabor
    Apr 24, 2015 at 21:44
  • What card do you have? Because I've got nv 760 and now I'm not so sure if it's safe to upgrade to 15.04 developer release. There is too much activity on askubuntu regarding the breakage of Nvidia proprietary driver after the update.
    – Velkan
    Apr 26, 2015 at 12:23
  • I've got a GeForce GT 620M, by the way 15.04 has been an official release when I got promted about the upgrade
    – Gabor
    Apr 28, 2015 at 7:59
  • May be it's a good time to give the nouveau driver a try ?
    – solsTiCe
    Apr 28, 2015 at 22:03

2 Answers 2

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I had a similar issue where the normal boot sequence got into a repeated failure pattern like your posted video shows. To be sure you can look at the log file /var/log/Xorg.0.log. In my case, I was able to boot into recovery mode, drop to a root shell, then install a different nvidia driver. In my case, nvidia-340 was installed after the upgrade to 15.04, and upgrading to nvidia-346 fixed it.

In case it helps, here are the steps I followed to fix this.
Problem booting after updating from Ubuntu 14.10 to 15.04

Good luck.

Dennis

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  • it did not help, and I updated my question to document this
    – Gabor
    Apr 28, 2015 at 9:36
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Until some easier procedure comes along for a noob such as myself, I reverted to the Noveaux driver, Nvidia 340.76 just makes Ubuntu 15.04 unstable.

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  • Did you try to upgrade your kernel as I suggested in the "Solution" above? It solved the issue for me, and is very simple and fast to do.
    – Gabor
    Jun 6, 2015 at 8:57

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