X11 forwarding request failed on channel 0

Obvious error with various sources and solutions. It appears mostly after fresh installation.

Symptom:

client:~/Desktop> ssh -v -XC root@server
OpenSSH_6.0p1, OpenSSL 1.0.1e 11 Feb 2013
...

debug1: Requesting X11 forwarding with authentication spoofing.
debug1: Requesting authentication agent forwarding.
debug1: Sending environment.
debug1: Sending env LANG = en_US.UTF-8
X11 forwarding request failed on channel 0

Solution:

server:~ # zypper in xauth
server:~ # vi /etc/ssh/sshd_config

in sshd_config  specify
AddressFamily inet

and restart sshd. IPv6 is disabled on client as well as on server.