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After starting the system, i've a black screen (without any screen backlight), then i have to switch to tty6 (ctrl+alt+f6), login and restart the lightdm:

sudo service lightdm restart

I'm using xfce.

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Can you please add to you r question what version of xubuntu you are using? – MadMike Oct 26 '13 at 14:14
possible duplicate of How can I restart x-server from the command line? – rds Nov 6 '13 at 19:50
up vote 2 down vote accepted

1st Way to solve your issue:

Try to reconfigure lightdm (if it doesn't solve your issue then go for Alternate way mentioned below.)

  • Open terminal(CTRL+ALT+T) and execute following command:

    sudo dpkg-reconfigre lightdm
  • Then chose lightdm from the list. As shown below:


  • Restart your system:

    sudo reboot now

It should fix your issue.

an alternate way, which would solve your issue. Give it a try.

Installing a new display manager can fix your problem. Steps to install GDM(a display manager much like lightdm):

  • Open terminal(CTRL+ALT+T) and execute following commands:

    sudo apt-get install gdm
    sudo dpkg-reconfigure lightdm

    then chose gdm from the list:


    sudo reboot
  • If it's still not fixed, try removing lightdm after installing gdm:

    sudo apt-get remove --purge lightdm
    sudo reboot

Reply if something goes wrong..

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After purge remove lightdm, i'd to change xfce theme back to graybird, but it's works. Thanks. – Zalazdi Oct 25 '13 at 18:12

If you are booting windows with ubuntu i have same problem then i tried everything referred from sites.finally nothing is worked for me.
so one thing is worked for me.

  1. do not choose the default ubuntu os.
  2. click on advanced option for ubuntu
  3. choose the os option like "Ubuntu 16.04 .....(Systemed)"

this will boot your ubuntu os normally. and it works for me also it saves your time to everytime restart lightdm service.

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