xrdp Can't open display.

[K4mey]

kamey@DESKTOP-NN9F1DD:~$ startxfce4 /usr/bin/startxfce4: X server already running on display :0.0 xrdb: Connection refused xrdb: Can't open display ':0.0' Unable to init server: Could not connect: Connection refused xfce4-session: Cannot open display: . Type 'xfce4-session --help' for usage.

Does anyone know what is the problem?