Response inconsistent on IIS

[SquaredMelon]

I am experiencing inconsistent behavior in the response of the remote SFTP server between the development machine and the production machine.

var ftpConf: {
        host: 'SFTP.____.IT', 
        username: '____', 
        password: '____',
        protocol: 'sftp',
        port: 22,
        escape: true,
        retries: 2, 
        timeout: 10, 
        retryInterval: 5,
        retryMultiplier: 1, 
        requiresPassword: true,
        autoConfirm: true,
        cwd: '', 
        directoryRemotaLotti: '/RX'
    },
var pathfileLotto = req.body.LottoFile;
var fileLottoName = pathfileLotto.substr(pathfileLotto.lastIndexOf('/')+1,pathfileLotto.length);
var fileLottoRename= fileLottoName.replace(".tmp", ".lat");
var ftps = new FTPS(config.ftpConf);
ftps
            .cd(config.ftpConf.directoryRemotaLotti)
            .addFile(pathfileLotto)
            .exec(function (err, result) {
                console.log('ERR=', err, 'RES=', result);
                if (!result.error) {
                    //res.json('OK')
                    ftps
                        .cd(config.ftpConf.directoryRemotaLotti)
                        .mv(fileLottoName, fileLottoRename)
                        .exec(function (err, result) {
                            console.log('ERR=', err, 'RES=', result);
                            if (!result.error) {
                                res.json('OK')
                            }
                            else {
                                res.status(500).json(err)
                            }
                            // err will be null (to respect async convention)
                            // res is an hash with { error: stderr || null, data: stdout }
                        });
                }
                else {
                    res.status(500).json(err)
                }
                // err will be null (to respect async convention)
                // res is an hash with { error: stderr || null, data: stdout }
            });

In DEV machine result in exec function return no error, in PROD machine return an error but the file is uploaded with success.

[____ for privacy]

ERR= null RES= { error: '2018-03-02 09:56:32 /cygdrive/e//../DocumentiComuni//2018/SS/FTA/P_SS_20180302-095549.tmp -> sftp://@SFTP..IT:22/RX/P_SS_20180302-095549.tmp 0-1599438 627.5 KiB/s\n', data: '' }

The PROD machine is a IIS 7.5 with iisnode on it.