I installed MDM, and found it's incompatible with my VGA hardware. After rebooting I see:

enter image description here

This screen repeats, even if I choose Yes or No

As I have access to the console (by pressing ALT+F2) I tried,

sudo dpkg-reconfigure lightdm

which gave me:

enter image description here

Even if I choose LightDM nothing happens at the next reboot. The first screen comes back!

$ dpkg -l | grep -i mdm
ii mdm                1.0.4-0~webupd8~precise        Gnome Display Mnager
ii mint-mdm-themes    1.0.5-0~webupd8~precise1       Linux Mint MDM Themes

I need LightDM login screen back!

  • Please share the content or output of the following commands/files to better help us troubleshoot your problem (instructions in this answer): command(s): dpkg -l | grep -i mdm – ish Sep 9 '12 at 4:17
  • I add it. Please see above... – Naveen Sep 9 '12 at 4:44

What the message is telling you is that lightdm is already running in the background. So, login to the console-session/terminal by pressing Alt+F2, or choose Exit to console login from the window below.

enter image description here

Now, remove MDM, using the commands below:

sudo apt-get purge mdm      
sudo dpkg -r mdm mint-mdm-themes

Set LightDM as default from this command:

sudo dpkg-reconfigure lightdm

Then reboot. MDM should be gone by now.

LightDM may start, but it's most likely to be in low graphics mode.

enter image description here

To fix this, you have to edit /etc/lightdm/lightdm.conf as following:


As you are unable to edit lightdm.conf through console-session, I may suggest using the Ubuntu Live CD.

(Using the live cd, enter gksu nautilus on terminal, then locate and open /media/yourUBUNTUpartition/etc/lightdm/lightdm.conf from Gedit... then you can do the editing!)

Considering that you haven't installed unity-greeter, download the package for Precise from here, and place it on /media/yourUBUNTUpartition/home/YourName.

That's it! Get out from the live CD and get back on the Console Session. (Alt + F2).

Now install the Unity-Greeter file you downloaded before:

sudo dpkg -i **unity-greeter_0.2.8-0ubuntu1_i386.deb** 

Finally start LightDM,

sudo service start lightdm
  • Um.... I already removed MDM, (but using sudo apt-get remove mdm) That's why it's not present on the 2nd screenshot..but I never removed mdm themes. Do you want me to remove gdm? – Naveen Sep 9 '12 at 4:55
  • Yes remove gdm AND run sudo apt-get purge gdm mdm\* – ish Sep 9 '12 at 4:57
  • Does the purge command need internet? Well, it will take some time for me to gain internet access...(Now I'm on a Windows machine) I reply you as soon as I do it. Thanks! – Naveen Sep 9 '12 at 5:02
  • No, no internet access is needed for purging. – ish Sep 9 '12 at 5:03
  • Great! Finally LightDM is back! Well, I ran into some other trouble while doing it.So I added that stuff too to your answer, if you don't mind. Thanks! – Naveen Sep 9 '12 at 9:02

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