@Martin thanks a lot it works fine!

I also could automatize my transfer with winscp.com adding -nopreservetime at the end of my put commands.

Have a nice day!

So does the connection always get lost after the MFMT command?
It might be a bug in the server.
You might be able to workaround it by disabling "Preserve timestamp" transfer setting:
https://winscp.net/eng/docs/ui_transfer_custom

Hello,
I'm looking to upload files to an FTP server from our Windows server. Unfortunately the connection gets lost as soon as I start the transfer with this message:

Disconnected from the server Copying files to the remote side failed.

I would like to point out that downloading files from this same server works fine. The disconnection also occurs using command lines with winscp.com.
I've already tried to allow winscp and winscp.com in Windows firewall of our server but it still disconnecting.

The same transfer (file and distant server) works fine from another local Windows machine. I attached logs of the working transfer (on my local machine) and the unworking one (from our Windows server). I see some small differences between the two but can't explain what goes wrong.

Thanks for your help