Help with Python - Error generating from FTP script

Hello, Experts,

I have a question to ask regarding a python script I have built to find a file, put in an array and SFTP that to a remote location that is running errors. The error I am getting is below.

Traceback (most recent call last):
  File "/Users/isaiah.melendez/Documents/python/alr_to_ho.py", line 38, in <module>
    ftpTransmit()
  File "/Users/isaiah.melendez/Documents/python/alr_to_ho.py", line 34, in ftpTransmit
    sftp.put(ftpALR[i], 'C:\CBASYNC')
  File "/Users/isaiah.melendez/Documents/python/venv/lib/python3.7/site-packages/pysftp/__init__.py", line 364, in put
    confirm=confirm)
  File "/Users/isaiah.melendez/Documents/python/venv/lib/python3.7/site-packages/paramiko/sftp_client.py", line 759, in put
    return self.putfo(fl, remotepath, file_size, callback, confirm)
  File "/Users/isaiah.melendez/Documents/python/venv/lib/python3.7/site-packages/paramiko/sftp_client.py", line 714, in putfo
    with self.file(remotepath, "wb") as fr:
  File "/Users/isaiah.melendez/Documents/python/venv/lib/python3.7/site-packages/paramiko/sftp_client.py", line 372, in open
    t, msg = self._request(CMD_OPEN, filename, imode, attrblock)
  File "/Users/isaiah.melendez/Documents/python/venv/lib/python3.7/site-packages/paramiko/sftp_client.py", line 813, in _request
    return self._read_response(num)
  File "/Users/isaiah.melendez/Documents/python/venv/lib/python3.7/site-packages/paramiko/sftp_client.py", line 865, in _read_response
    self._convert_status(msg)
  File "/Users/isaiah.melendez/Documents/python/venv/lib/python3.7/site-packages/paramiko/sftp_client.py", line 898, in _convert_status
    raise IOError(text)
OSError

Python Code:

#import libraries
import os
import pysftp
from locker import *

# query for file function
alr_file = '/Users/isaiah.melendez/Documents/python/test'
#alr_file = 'C:\TBOffice\TBOLink\TEK\Export'
#prep list to store data in
ftpALR = []

ftp_un_dec = cipher_suite.decrypt(cipher_text2)
ftp_pw_dec = cipher_suite.decrypt(cipher_text)

#look for file and store in list and iterate
def findFile():

    for item in os.listdir(alr_file):
        if item.endswith('.mdb'):
            #ftpALR.append(alr_file + '\\' + item)
            ftpALR.append(alr_file + '/' + item)
            #print(ftpALR)

# ftp transmission function
def ftpTransmit():
    # list ftp dir
    cnopts = pysftp.CnOpts()
    cnopts.hostkeys = None
    with pysftp.Connection(host='co2.cbapps.com', username=ftp_un_dec.decode('utf-8'), password=ftp_pw_dec.decode('utf-8'), port=2222, cnopts=cnopts) as sftp:

        length = len(ftpALR)

        for i in range(length):
            sftp.put(ftpALR[i], 'C:\CBASYNC')
    
    print("Transmission Success")
findFile()
ftpTransmit()

I have the user credentials being passed by a locker.py file and imported into this file.

Let me know your thoughts as to why this might be happening?