Python 2.7 : retrieve netCDF4 file with ftplib - python-2.7

Question

Here is my issue :
I download some netCDF4 files from an FTP server, in two different ways: via FileZilla and via a Python 2.7 script using ftplib.
Code of Python script (running on Windows) :
# download the file
try:
ftp = FTP(server_address)
ftp.login(server_login, server_pass)
filepath = 'the_remote_rep/myNetCDF4File.nc'
filename = 'myNetCDF4File.nc'
local_dir = 'toto'
new_file = open('%s/%s' % (local_dir, filename), "w")
ftp.retrbinary('RETR %s' % filepath, new_file.write)
ftp.close()
new_file.close()
except Exception as e:
print("Error FTP : '" + str(e) + "'")
# update title into the file
try:
fname = 'toto/myNetCDF4File.nc'
dataset = netCDF4.Dataset(fname, mode='a')
setattr(dataset, 'title', 'In Situ Observation Re-Analysis')
dataset.close()
except Exception as e:
print("Error netCDF4 : '" + str(e) + "'")
Then, I get this message :
Error netCDF4 : '[Errno 22] Invalid argument: 'toto/myNetCDF4File.nc''
When I try the second block of code with a netCDF4 file downloaded via FileZilla (the same file for example), there is no error.
Also, when I try to get the netCDF version of the file using "ncdump -k", here is the response (OK with the other file) :
ncdump: myNetCDF4File.nc: Invalid argument
In addition, files do not have the same size depending on the method :
FileZilla : 22 972 Ko
Python ftplib : 23 005 Ko
Is it a problem from ftplib when writing the retrieved file? Or did I miss some parameters to correctly encode the file?
Thanks in advance.
EDIT : verbose messages from FileZilla :
...
Response: 230 Login successful.
Trace: CFtpLogonOpData::ParseResponse() in state 5
Trace: CControlSocket::SendNextCommand()
Trace: CFtpLogonOpData::Send() in state 9
Command: OPTS UTF8 ON
Trace: CFtpControlSocket::OnReceive()
Response: 200 Always in UTF8 mode.
Trace: CFtpLogonOpData::ParseResponse() in state 9
Status: Logged in
Trace: Measured latency of 114 ms
Trace: CFtpControlSocket::ResetOperation(0)
Trace: CControlSocket::ResetOperation(0)
Trace: CFtpLogonOpData::Reset(0) in state 14
Trace: CFtpControlSocket::FileTransfer()
Trace: CControlSocket::SendNextCommand()
Trace: CFtpFileTransferOpData::Send() in state 0
Status: Starting download of /INSITU_OBSERVATIONS/myNetCDF4File.nc
Trace: CFtpChangeDirOpData::Send() in state 0
Trace: CFtpControlSocket::ResetOperation(0)
Trace: CControlSocket::ResetOperation(0)
Trace: CFtpChangeDirOpData::Reset(0) in state 0
Trace: CFtpFileTransferOpData::SubcommandResult(0) in state 1
Trace: CControlSocket::SendNextCommand()
Trace: CFtpFileTransferOpData::Send() in state 5
Trace: CFtpRawTransferOpData::Send() in state 2
Command: PASV
Trace: CFtpControlSocket::OnReceive()
Response: 227 Entering Passive Mode (193,68,190,45,179,16).
Trace: CFtpRawTransferOpData::ParseResponse() in state 2
Trace: CControlSocket::SendNextCommand()
Trace: CFtpRawTransferOpData::Send() in state 4
Trace: Binding data connection source IP to control connection source IP 134.xx.xx.xx
Command: RETR myNetCDF4File.nc
Trace: CTransferSocket::OnConnect
Trace: CFtpControlSocket::OnReceive()
Response: 150 Opening BINARY mode data connection for myNetCDF4File.nc (9411620 bytes).
Trace: CFtpRawTransferOpData::ParseResponse() in state 4
Trace: CControlSocket::SendNextCommand()
Trace: CFtpRawTransferOpData::Send() in state 5
Trace: CTransferSocket::TransferEnd(1)
Trace: CFtpControlSocket::TransferEnd()
Trace: CFtpControlSocket::OnReceive()
Response: 226 Transfer complete.
Trace: CFtpRawTransferOpData::ParseResponse() in state 7
Trace: CFtpControlSocket::ResetOperation(0)
Trace: CControlSocket::ResetOperation(0)
Trace: CFtpRawTransferOpData::Reset(0) in state 7
Trace: CFtpFileTransferOpData::SubcommandResult(0) in state 7
Trace: CFtpControlSocket::ResetOperation(0)
Trace: CControlSocket::ResetOperation(0)
Trace: CFtpFileTransferOpData::Reset(0) in state 7
Status: File transfer successful, transferred 9 411 620 bytes in 89 seconds
Status: Disconnected from server
Trace: CFtpControlSocket::ResetOperation(66)
Trace: CControlSocket::ResetOperation(66)

Answer 1

In fact, this is a problem of binary configuration (thanks to your questions).
I added ftp.voidcmd('TYPE I') before retrieving file with ftplib, then I modified writing parameter of local file as new_file = open('%s/%s' % (local_ftp_path, filename), "wb") to specify that's a binary file.
Now the file is readable after download via ftplib and has same size as downloaded from FileZilla.
Thanks to your contribution.