I used to use Cinnamon as my desktop environment on 17.10. After I updated to 18.10 I reinstalled Cinnamon using sudo apt-get install cinnamon-desktop-environment but can no longer log in to that specific environment.
After I type in my password there is a pause, the screen goes black, and then returns to the original log in screen.
I am able to start Cinnamon from the terminal when I am already in another session (I use xfce otherwise) using cinnamon --replace and everything works as expected.
I have also tried lightdm and gdm3 both with the same result (in fact gdm3 won't let me boot into xfce, but it will let me boot into gnome). And setting the ownership of my home directory with chown -R $USER:$USER /home/$USER
I am not sure what sort of error log information I should add to this post that would help, but I can add any suggestions from the comments.