ERROR: Unable to load a failsafe session

[whoslucifer]

What is the cause of this error

startxfce4
/usr/bin/startxfce4: X server already running on display :0
/bin/sh: 0: cannot open /etc/xdg/xfce4/xinitrc: Permission denied

sudo startxfce4
[sudo] password for asherah:
/usr/bin/startxfce4: X server already running on display :0
Authorization required, but no authorization protocol specified

xrdb: Resource temporarily unavailable
xrdb: Can't open display ':0'
dbus-update-activation-environment: error: unable to connect to D-Bus: /usr/bin/dbus-launch terminated abnormally without any error message

(process:89814): xfce4-session-CRITICAL **: 18:16:15.101: dbus-launch not found, the desktop will not work properly!
Authorization required, but no authorization protocol specified

xfce4-session: Cannot open display: .
Type 'xfce4-session --help' for usage.

[whoslucifer]

Its an xfce issue