Installed Ubuntu 19.04 and fix the dependency issue with https://askubuntu.com/questions/1135065/ubuntu-19-04-libwebkitgtk-1-0-so-0-missing
Now I can log vpn successfully :-)
It appears that for some users it's working.
Actually for myself, I tried on Fedora with kernel 5 and it works. Only in Ubuntu with versions > 4.15 I couldn't make it work.
It would be helpful and kind if you would make a statement about the status of this issue.