Ubuntu: 16.10 Lightdm failed to start session with i3


I have just done a clean server install and run:

sudo apt-get install lightdm i3  

The problem is if I reboot and enter my password at the LightDM screen I get the following error: failed to start session. If I check the logs I have the following error:

DEBUG: Seat: Failed to find session configuration ubuntu  DEBUG: Seat: Can't find session 'ubuntu'  

I did some googling and the only suggestion that got me anywhere was:

sudo apt-get install ubuntu-session  

Now if I log in using LightDM I get into a screen but none of my i3 commands work, it does not even take me through the tutorial.

I am guessing I am in some sort of desktop session without a window manager but this is all new territory for me so any clarification would be great.


Okay so I finally got this working by taking the following steps.

1) Clean install of ubuntu (minimal or server)

2) sudo apt-get install lightdm i3

3) sudo reboot

4) Try to login at LightDM screen get the failed to start session error

5) Hit TAB + ENTER to access session picker (my mouse doesn't work until I install drivers but you could use yours) and 're-select' i3

6) Try to login again, this time it boots to a black screen

7) Use CTRL + ALT + F1 to get to a tty and run sudo reboot

8) Login using LightDM and the i3 config wizard starts and I am able to use my desktop.

I am guessing that step 5-6 are setting the session and creating any necisary files that for some reason do not exist and after that point it is easy to login.


I think it was because at the first time, the default session was ubuntu in the /etc/lightdm/lightdm.conf file (if you don't have it you can create it), so when it was looking for it, it did noy find it.

Under the [SeatDefaults] you can find user-session=ubuntu

This has to be changed to:user-session=i3

All in all, it has to be

[SeatDefaults]  greeter-session=$WHATEVERGREETER  user-session=i3  

This is just a speculation, but that is what you have actually done with step5. Maybe this way can also help some people.

Note:If u also have question or solution just comment us below or mail us on toontricks1994@gmail.com
Next Post »