We faced the same issue while trying to copy files to an FTPS server. 
We are trying to connect to a Filezilla server. The type of encryption we are using for the FTPS is 'Require explicit FTP over TLS'.

There are the errors that my colleague and I had while trying to use the ftp.nlst() or the storbinary() functions in ftplib. 

EOF occurred in violation of protocol (_ssl.c:852)
OSError: [Errno 0] Error
 
After some research on the internet, we found a workaround on stack overflow (https://stackoverflow.com/questions/46633536/getting-a-oserror-when-trying-to-list-ftp-directories-in-python) 

Below is the code for the workaround. hoping this could help resolve the issue in the newer version. 
 
import ftplib
from ssl import SSLSocket


class ReusedSslSocket(SSLSocket):
    def unwrap(self):
        pass


class MyFTP_TLS(ftplib.FTP_TLS):
    """Explicit FTPS, with shared TLS session"""
    def ntransfercmd(self, cmd, rest=None):
        conn, size = ftplib.FTP.ntransfercmd(self, cmd, rest)
        if self._prot_p:
            conn = self.context.wrap_socket(conn,
                                            server_hostname=self.host,
                                            session=self.sock.session)  # reuses TLS session            
            conn.__class__ = ReusedSslSocket  # we should not close reused ssl socket when file transfers finish
        return conn, size