Scan failed (-1): Connection closed(23) : 200 Type set to I.
This error can be caused by security software such as Symantec EndPoint Network Protection. If enabled, please disable it or configure it as appropriate.
The debug log (if enabled) will also contain the following lines:
An established connection was aborted by the software in your host machine.
Server closed connection
You may also get this error if the option "Try to keep the connection alive during file transfers" is enabled (on the FTP->Firewall settings page).