When developing OpenSSL Library for .NET we take extra care no to brake backward compatibility. Yet, sometimes this happens.
This page notes some code refactoring steps needed in order to migrate from older versions of the library. If nothing is listed here regarding your current version, then no code changes are need.
From 1.2.x to 1.3.x
1) Replace DidiSoft.OpenSsl.Dh.OpenSslDh.DhKeyLeght with DidiSoft.OpenSsl.KeyLegth
2) Replace DidiSoft.OpenSsl.Dsa.OpenSslDsa.DsaKeyLeght with DidiSoft.OpenSsl.KeyLegth
3) Replace DidiSoft.OpenSsl.Rsa.OpenSslRsa.RsaKeyLeght with DidiSoft.OpenSsl.KeyLegth