[Python] Can't Upload to FTPS using Python's Ftplib

I have a script that I want to run daily via Cron that would first download files and upload files from a local directory to FTPS server.

I have created this script:

import ftplib
import ssl
import socket
import os
import io

# --- Configuration ---
host = 'XXX' # Replace with actual server
port = 990 # Implicit FTPS
username = 'XXX' # Replace with your username
password = 'XXX' # Replace with your password
download_from_dir = '/users/Outbound'
upload_to_dir = '/users/Outbound'
local_download_dir = './Download' # Change as needed
local_upload_dir = '/home/ilfs/Public/tals-datasets/2025-07-25'

BLOCKSIZE = 128 * 1024 # 256 KB

# --- Ensure local download folder exists ---
os.makedirs(local_download_dir, exist_ok=True)

# --- Create SSL context for Implicit FTPS ---
context = ssl.create_default_context()
context.check_hostname = False
context.verify_mode = ssl.CERT_NONE

# --- Connect and wrap socket manually ---
sock = socket.create_connection((host, port))
ssl_sock = context.wrap_socket(sock, server_hostname=host)

ftp = ftplib.FTP_TLS()
ftp.sock = ssl_sock
ftp.af = socket.AF_INET
ftp.file = io.TextIOWrapper(ssl_sock.makefile('rb'), encoding='utf-8', newline='\r\n')
ftp.welcome = ftp.getresp()
ftp.prot_p()
ftp.login(username, password)
ftp.set_pasv(True)
ftp.host = host # override unroutable passive IP

# ========== DOWNLOAD SECTION ==========
print(f"\n Connecting to remote download folder: {download_from_dir}")
ftp.cwd(download_from_dir)
files = ftp.nlst()
print(f" Found {len(files)} files to download...\n")

for fname in files:
local_path = os.path.join(local_download_dir, fname)
print(f"⬇ Downloading: {fname}")
with open(local_path, 'wb') as f:
ftp.retrbinary(f"RETR {fname}", f.write, blocksize=BLOCKSIZE)
print("✅ All downloads complete.\n")

# ========== UPLOAD SECTION ==========
print(f" Switching to upload directory: {upload_to_dir}")

local_files = [f for f in os.listdir(local_upload_dir) if os.path.isfile(os.path.join(local_upload_dir, f))]

ftp.cwd(upload_to_dir)
ftp.set_pasv(True)
ftp.host = host

for fname in local_files:
local_path = os.path.join(local_upload_dir, fname)
if os.path.isfile(local_path):
safe_name = fname.replace(" ", "_").replace(":", "-")
print(f"⬆ Uploading: {safe_name}")
try:
with open(local_path, 'rb') as f:
ftp.storbinary(f"STOR {safe_name}", f, blocksize=128*1024)
ftp.voidcmd("NOOP")
print(f" ✅ Uploaded: {safe_name}")
except Exception as e:
print(f" ❌ Failed to upload {safe_name}: {e}")
ftp.quit()
print(" All done.")


The problem is download works, but I am failing to upload files. I have tried whatever I could, but only the first file gets uploaded, others failed.

Connecting to remote download folder: /users//Outbound
Found 10 files to download...

⬇ Downloading: 07-25-2025_XXXXXXXXXXXX.txt
⬇ Downloading: 07-25-2025_XXXXXXXXXXXX.txt
⬇ Downloading: 07-25-2025_XXXXXXXXXXXX.txt
⬇ Downloading: 07-25-2025_XXXXXXXXXXXX.txt
✅ All downloads complete.

Switching to upload directory: /users/Outbound
⬆ Uploading: 07-25-2025_XXXXXXXXXXXX.txt
❌ Failed to 07-25-2025_XXXXXXXXXXXX.txt: [SSL: UNEXPECTED_EOF_WHILE_READING] EOF occurred in violation of protocol (_ssl.c:2685)
⬆ Uploading: 07-25-2025_XXXXXXXXXXXX.txt
❌ Failed to upload 07-25-2025_XXXXXXXXXXXX.txt: 426 Transfer failed
⬆ Uploading: 07-25-2025_XXXXXXXXXXXX.txt
❌ Failed to upload 07-25-2025_XXXXXXXXXXXX.txt: 200 Transfer mode set to BINARY
⬆ Uploading: 07-25-2025_XXXXXXXXXXXX.txt
❌ Failed to upload 07-25-2025_XXXXXXXXXXXX.txt: 200 Transfer mode set to BINARY
⬆ Uploading: 07-25-2025_XXXXXXXXXXXX.txt
❌ Failed to upload 07-25-2025_XXXXXXXXXXXX.txt: 200 Transfer mode set to BINARY


All done.

What should I do? The uploads are only working in Filezilla and in .NET with FluentFtp. In Filezilla i get this status: Status: Server sent passive reply with unroutable address. Using server address instead.

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