In the /etc/init/lightdm.conf file adding some delay before executing lightdm solves the problem for me:
sleep 10
exec lightdm
This way I can also see the Ubuntu boot screen with the progress bar which I never saw before. It was just the plain background color flashing a couple of times quickly (I have an SSD drive) and after that in the lucky cases the login screen showed up, other cases I had to start lightdm manually.
In the /etc/init/ lightdm. conf file adding some delay before executing lightdm solves the problem for me:
sleep 10
exec lightdm
This way I can also see the Ubuntu boot screen with the progress bar which I never saw before. It was just the plain background color flashing a couple of times quickly (I have an SSD drive) and after that in the lucky cases the login screen showed up, other cases I had to start lightdm manually.