One more thing: remove .ganttproject file from your home folder.
Thank you Dmitry, I appreciate you’re trying hard… but it still does not work. I really can’t figure out how this had worked at first install and no more.
One thing that I have no idea if this helps: in my user home folder, I have many gantproject.log.1 and gantproject.log.1.lck
I have deleted these “log” files… and it’s worked, though I don’t know whether it is relevant. It seems I have now access to your beautiful tool.
Thanks a lot for your help !