This is the short story: I was trying to implement google OTP authentication while connecting to openvpn, so that in addition to normal password you need to pass timed token generated by your mobile app. My OS was CentOS 7.
The problem was that it didn't work after following some instruction on the web. (like this one http://dillidba.blogspot.com/2017/02/install-openvpn-on-centos-with-google.html)
My openvpn log was showing this error:
