Python ftplib fails with "Policy requires SSL" even when FTP_TLS is used

Question

I'm trying to use ftplib to connect to an FTP server to download a set of files. When I try to create the connection, I keep getting a 534 Policy requires SSL error.

Code:

from ftplib import FTP_TLS
import pandas

ftp = FTP_TLS(host="ftp._____.com", user="____", passwd="____")

ftp.login(user="______", passwd="______")
ftp.cwd("DIR/")
ftp.dir()

Error log:

*cmd* 'USER ********'
*put* 'USER ********\r\n'
*get* '331 Password required\n'
*resp* '331 Password required'
*cmd* 'PASS ********'
*put* 'PASS ********\r\n'
*get* '230 User logged in.\n'
*resp* '230 User logged in.'
*cmd* 'CWD ______/'
*put* 'CWD ______/\r\n'
*get* '250 CWD command successful.\n'
*resp* '250 CWD command successful.'
*cmd* 'TYPE A'
*put* 'TYPE A\r\n'
*get* '200 Type set to A.\n'
*resp* '200 Type set to A.'
*cmd* 'PASV'
*put* 'PASV\r\n'
*get* '227 Entering Passive Mode (13,64,237,64,19,157).\n'
*resp* '227 Entering Passive Mode (13,64,237,64,19,157).'
*cmd* 'LIST'
*put* 'LIST\r\n'
*get* '534 Policy requires SSL.\n'
*resp* '534 Policy requires SSL.'
Traceback (most recent call last):
  File "xb_shipped.py", line 20, in <module>
    ftp.dir()
  File "C:\Users\main\AppData\Local\Programs\Python\Python38-32\lib\ftplib.py", line 558, in dir
    self.retrlines(cmd, func)
  File "C:\Users\main\AppData\Local\Programs\Python\Python38-32\lib\ftplib.py", line 451, in retrlines
    with self.transfercmd(cmd) as conn, \
  File "C:\Users\main\AppData\Local\Programs\Python\Python38-32\lib\ftplib.py", line 382, in transfercmd
    return self.ntransfercmd(cmd, rest)[0]
  File "C:\Users\main\AppData\Local\Programs\Python\Python38-32\lib\ftplib.py", line 781, in ntransfercmd
    conn, size = FTP.ntransfercmd(self, cmd, rest)
  File "C:\Users\main\AppData\Local\Programs\Python\Python38-32\lib\ftplib.py", line 348, in ntransfercmd
    resp = self.sendcmd(cmd)
  File "C:\Users\main\AppData\Local\Programs\Python\Python38-32\lib\ftplib.py", line 275, in sendcmd
    return self.getresp()
  File "C:\Users\main\AppData\Local\Programs\Python\Python38-32\lib\ftplib.py", line 248, in getresp
    raise error_perm(resp)
ftplib.error_perm: 534 Policy requires SSL.

I have also tried to use the solution found here: https://stackoverflow.com/questions/55814722/cannot-list-ftp-directory-using-ftplib-but-ftp-client-works/55874794#55874794

But this solution gives me the same error:

Code:

from ftplib import FTP_TLS
import pandas


class SmartFTP(FTP_TLS):
    def makepasv(self):
        invalidhost, port = super(SmartFTP, self).makepasv()
        return self.host, port

ftp_server = 'ftp.____.com'
ftp = SmartFTP(ftp_server)
ftp.login(user="____", passwd="____")
ftp.cwd("DIR/")
ftp.dir()

Answer 1

You have to call FTP_TLS.prot_p to enable TLS/SSL encryption on the data channel:

ftp = FTP_TLS(ftp_server)
ftp.login(user=user, passwd=passwd)
ftp.prot_p()