Problem:
I connected to my server with X forwarding using
ssh -CX user@server
but when I start a graphical application on the server, I see the following error messages:
user@server $ gparted X11 connection rejected because of wrong authentication. Unable to init server: Could not connect: Connection refused (gpartedbin:70357): Gtk-WARNING **: 00:06:19.612: cannot open display: localhost:11.0
Solution:
I found the solution in this StackOverflow post:
sudo --preserve-env=DISPLAY -s xauth merge /home/user/.Xauthority
Note that you have to replace /home/user
with the appropriate home directory.