Xfce - Unable to load a failsafe session finally solved

This time I got this error after having installed Xfce on my parents' PC:

Unable to load failsafe session
Unable to determine a failsafe session name. Possible causes:
xfconfd isn't running (D-Bus setup problem);
environment variable $XDG_CONFIG_DIRS is set incorrectly (must include "/etc"),
or xfce4-session is installed incorrectly

I found some threads about this error where people suggested:
- Installing dbus
- Restarting dbus
- Fixing home folder permissions
- Reinstalling Xfce
and more...

None of the suggestions worked for me. Then I noticed a weird error in terminal that said something like:

mkdir: cannot create directory `/root/.config': Permission denied

I was pretty sure I was trying to start Xfce under a non-root user, though, so why would it use /root as my users home directory?

It turned out my user's $XDG_CONFIG_HOME variable was set to /home/root/.config, which was wrong, obviously.

Setting it to /home/myuser/.config solved the issue and let me start Xfce flawlessly again:

XDG_CONFIG_HOME=/home/myuser/.config

Not sure if it had to do with SLiM DM I installed earlier or something else.