I ran into this error today while running a python program in Kubuntu 18.04 (upgraded from 17.10):
qt.network.ssl: QSslSocket: cannot call unresolved function SSLv23_client_method
followed by a bunch of other similar SSL-related errors. When I checked apt, I found that my openSSL install was fine. A generous guy on IRC informed me that I was very likely missing libraries that the app was looking for. S/he asked me to try installing libssl1.0-dev and voila, it worked.