I recently had reported installing x2goserver on a totally new server machine and the x2goclient on a totally new client machine both running Ubuntu 12.04 beta 2 and the fact that when trying to start an x2go session it would always indicate "running" then immediately fail/terminate.
I've found out the following.
After adding the x2go PPA for debian/ubuntu
*sudo add-apt-repository ppa:x2go/stable sudo apt-get update*
In the past all I've had to do on the server was install x2goserver
*sudo apt-get install x2goserver*
then edit /etc/ssh/sshd_config and enable ChallengeResponseAuthentication to YES
*ChallengeResponseAuthentication yes*
However, with the new x2go versions apparently that is NOT they only module that needs to be installed.
On the server you now also must install x2goserver-xsession * sudo apt-get install x2goserver-xsession*
My best guess is that this was introduced when the new x2go versions implemented the ability to *published apps* on the x2go server without having to install any sort of desktop environment on the remote "server" machine.
After installing the x2goserver-xsession the x2goclient now successfully creates a remote desktop session with one caveate... I've had to setup the remote server for ssh automatic login
If using Ubuntu refer to: https://help.ubuntu.com/community/SSH/OpenSSH/Keys
If I do not do this then the login to the remote server will always fail due to some ssh failure but I am not sure if its the client or server side that fails but that is another problem to figure out later. At least I can get a remote desktop now.
I'm not sure if the above change was documented anywhere on the x2go wiki but I will check and add it if it doesn't exist yet.
Brian