Yes deleting /tmp/.x2go-$USER did fix it. It happens rarely. I'm not sure how long the session runs before this occurs. A fix for this issue would be great. Thanks for the suggestion!
Uh, no, my suggestion was *not* to delete this data, it was to make sure that *nothing* deletes this data in the first place.
Congrats, in the best case x2gocleansessions killed the session after the metadata vanished, in the worst case you have a stale x2goagent/nxagent process still running...
Mihai