Searching the Web for "lightdm.service: Failed with result 'start-limit-hit'"
returns similar problems. The configuration of LightDM seems faulty in all
cases. For information, I only have one file "users.conf" and an empty
"lightdm.conf.d" directory in /etc/lightdm:
$ ls /etc/lightdm/*
/etc/lightdm/users.conf
/etc/lightdm/lightdm.conf.d:
Here is the content of my "/etc/lightdm/users.conf" (I believe it is
Trisquel's default):
$ cat /etc/lightdm/users.conf
#
# User accounts configuration
#
# NOTE: If you have AccountsService installed on your system, then LightDM
will
# use this instead and these settings will be ignored
#
# minimum-uid = Minimum UID required to be shown in greeter
# hidden-users = Users that are not shown to the user
# hidden-shells = Shells that indicate a user cannot login
#
[UserList]
minimum-uid=500
hidden-users=nobody nobody4 noaccess
hidden-shells=/bin/false /usr/sbin/nologin
However I (and probably you) "have AccountsService installed". I believe
(part of?) the configuration is then in /usr/share/lightdm/lightdm.conf.d:
$ ls /usr/share/lightdm/lightdm.conf.d
50-disable-log-backup.conf 50-greeter-wrapper.conf 50-guest-wrapper.conf
50-ubuntu-mate.conf 50-unity-greeter.conf 50-xserver-command.conf
Those files actually do not contain much:
$ cat /usr/share/lightdm/lightdm.conf.d/*
[LightDM]
# Disable log backup - we use logrotate instead
backup-logs=false
[Seat:*]
greeter-wrapper=/usr/lib/lightdm/lightdm-greeter-session
[Seat:*]
guest-wrapper=/usr/lib/lightdm/lightdm-guest-session
[Seat:*]
user-session=mate
[Seat:*]
greeter-session=unity-greeter
[Seat:*]
# Dump core
xserver-command=X -core
Maybe you removed the so-called "greeter"? Do you have the the
"unity-greeter" package installed (it includes in particular the graphics for
the login screen)? Try to install it:
$ sudo apt install unity-greeter
As a side note, 'journalctl' allows you to only read the messages that relate
to a specific unit (such as the LightDM service):
$ journalctl -u lightdm
