Connection has been unexpectedly closed. Server sent command

Error: "Connection has been unexpectedly closed. Server sent command exit status 0."

Hi Friends,

I am able to connect to a FTP server using WinSCP GUI, but same is not working through C# code.
I am using "Server name", "Username" and "PrivateKeyFile" (Note: No password)

But when trying to connect through C# script throwing an error message stated above.
my script something like:

SessionOptions sessionOptions = new SessionOptions
{
Protocol = Protocol.Sftp,
HostName = (string) Dts.Variables["User::HostName"].Value,
UserName = (string) Dts.Variables["User::UserName"].Value,
//Password = (string) Dts.Variables["User::Password"].Value,
PortNumber = 22,
SshHostKeyFingerprint = "ssh-rsa 2048 xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx"
};

try
{

using (Session session = new Session())
{
session.ExecutablePath = @"E:\Program Files (x86)\WinSCP\winscp.exe";

// Connect
session.Open(sessionOptions);

// Upload files
TransferOptions transferOptions = new TransferOptions();
transferOptions.TransferMode = TransferMode.Binary;
MessageBox.Show("transfer mode set");

TransferOperationResult transferResult;
transferResult = session.PutFiles(@"" + localPath + "\\" + extractfilename + ".txt", "/home/Vulcan/", false, transferOptions);

// Throw on any error
transferResult.Check();
MessageBox.Show("successful upload");

// Print results
bool fireAgain = false;
foreach (TransferEventArgs transfer in transferResult.Transfers)
{
Dts.Events.FireInformation(0, null,
string.Format("Upload of {0} succeeded", transfer.FileName),
null, 0, ref fireAgain);
}


I enable logging in WinSCP GUI and having information(below), may this helps.

Session name: user_xyz@servername.abc.com (Modified stored session)
Host name: servername.abc.com (Port: 22)
User name: user_xyz (Password: No, Key file: Yes)
Tunnel: No
Transfer Protocol: SFTP (SCP)
Ping type: -, Ping interval: 30 sec; Timeout: 15 sec
Proxy: none
SSH protocol version: 2; Compression: No
Bypass authentication: No
Try agent: Yes; Agent forwarding: No; TIS/CryptoCard: No; KI: Yes; GSSAPI: No
Ciphers: aes,blowfish,3des,WARN,arcfour,des; Ssh2DES: No
SSH Bugs: A,A,A,A,A,A,A,A,A,A
Return code variable: Autodetect; Lookup user groups: A
Shell: default
EOL: 0, UTF: 2
Clear aliases: Yes, Unset nat.vars: Yes, Resolve symlinks: Yes
LS: ls -la, Ign LS warn: Yes, Scp1 Comp: No
SFTP Bugs: A,A
SFTP Server: default
Local directory: default, Remote directory: home, Update: Yes, Cache: Yes
Cache directory changes: Yes, Permanent: Yes
DST mode: 1; Timezone offset: 0h 0m
--------------------------------------------------------------------------
Looking up host "servername.abc.com"
Connecting to xx.xx.xx.xxx port 22
Server version: SSH-2.0-OpenSSH_5.3
Using SSH protocol version 2
We claim version: SSH-2.0-WinSCP_release_5.1.5
Doing Diffie-Hellman group exchange
Doing Diffie-Hellman key exchange with hash SHA-1
Verifying host key rsa2 0x23,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 with fingerprint ssh-rsa 2048 xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx
Host key matches cached key
Host key fingerprint is:
ssh-rsa 2048 xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx
Initialised AES-256 SDCTR client->server encryption
Initialised HMAC-SHA1 client->server MAC algorithm
Initialised AES-256 SDCTR server->client encryption
Initialised HMAC-SHA1 server->client MAC algorithm
Reading private key file "E:\Program Files (x86)\WinSCP\PuTTY\myPrivateKeyFile.ppk"
Using username "user_xyz".
Offered public key
Offer of public key accepted
Authenticating with public key "rsa-key-20140220"
Sent public key signature
Access granted
Opened channel for session
Started a shell/command
--------------------------------------------------------------------------
Using SFTP protocol.
Doing startup conversation with host.
Type: SSH_FXP_INIT, Size: 5, Number: -1
Type: SSH_FXP_VERSION, Size: 95, Number: -1
SFTP version 3 negotiated.
Unknown server extension posix-rename@openssh.com="1"
Unknown server extension statvfs@openssh.com="2"
Unknown server extension fstatvfs@openssh.com="2"
We believe the server has signed timestamps bug
We will use UTF-8 strings for status messages only
Limiting packet size to OpenSSH sftp-server limit of 262148 bytes
Getting current directory name.
Getting real path for '.'
Type: SSH_FXP_REALPATH, Size: 10, Number: 1552
Type: SSH_FXP_NAME, Size: 45, Number: 1552
Real path is '/home/Vulcan'
Listing directory "/home/Vulcan".
Type: SSH_FXP_OPENDIR, Size: 21, Number: 1803
Type: SSH_FXP_HANDLE, Size: 13, Number: 1803
Type: SSH_FXP_READDIR, Size: 13, Number: 2060
Type: SSH_FXP_NAME, Size: 889, Number: 2060
Type: SSH_FXP_READDIR, Size: 13, Number: 2316
Type: SSH_FXP_STATUS, Size: 28, Number: 2316
Status code: 1
Type: SSH_FXP_CLOSE, Size: 13, Number: 2564
.ssh;d;4096;2014-02-20T09:26:53.000Z;"Vulcan" [7382];"Vulcangrp" [17234];rwx------;2
testfile;-;0;2014-02-20T07:31:43.000Z;"root" [0];"root" [0];rw-r--r--;0
.bashrc;-;124;2013-07-09T13:24:50.000Z;"Vulcan" [7382];"Vulcangrp" [17234];rw-r--r--;2
.bash_profile;-;176;2013-07-09T13:24:50.000Z;"Vulcan" [7382];"Vulcangrp" [17234];rw-r--r--;2
..;d;12288;2014-02-20T07:19:30.000Z;"root" [0];"root" [0];rwxr-xr-x;0
.kshrc;-;121;2013-05-16T13:24:27.000Z;"Vulcan" [7382];"Vulcangrp" [17234];rw-r--r--;2
.bash_logout;-;18;2013-07-09T13:24:50.000Z;"Vulcan" [7382];"Vulcangrp" [17234];rw-r--r--;2
Startup conversation with host finished.

NOTE: I have modified the confidential information here (e.g. servername, username, fingerprintkey, etc)

Please help me to know the possible reason of failure. Your help is highly appreciated. :)

Please attach a full session log file showing the problem (using the latest version of WinSCP).