System.TypeInitializationException was unhandled
Message: An unhandled exception of type 'System.TypeInitializationException' occurred in mscorlib.dll
Additional information: The type initializer for 'XXXXX' threw an exception.

using (Session sess = new Session())
{
    //sess.SessionLogPath = @"C:\GUR";
    sess.Open(sessionOptions);
                    
    //Get Ftp File
    TransferOptions transferOptions = new TransferOptions();
    transferOptions.TransferMode = TransferMode.Binary; //The Transfer Mode -                 
    transferOptions.FilePermissions = new FilePermissions(0666); //Permissions applied to remote files. 0666 is read/write                
    transferOptions.PreserveTimestamp = false; //Set last write time of                 
    transferOptions.ResumeSupport.State = TransferResumeSupportState.Off;
    
    TransferOperationResult transferResult;                
    transferResult = sess.PutFiles(fileName, ConfigurationManager.AppSettings["SFTPToPath"], false, transferOptions);
    
    transferResult.Check();                
}

mscorlib.dll!System.IO.__Error.WinIOError(int errorCode, string maybeFullPath) + 0x321 bytes
mscorlib.dll!System.IO.FileStream.Init(string path, System.IO.FileMode mode, System.IO.FileAccess access, int rights, bool useRights, System.IO.FileShare share, int bufferSize, System.IO.FileOptions options, Microsoft.Win32.Win32Native.SECURITY_ATTRIBUTES secAttrs, string msgPath, bool bFromProxy, bool useLongPath) + 0x477 bytes
mscorlib.dll!System.IO.FileStream.FileStream(string path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share) + 0x54 bytes
mscorlib.dll!System.IO.File.Open(string path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share) + 0x25 bytes
WinSCPnet.dll!WinSCP.SessionLogReader.OpenLog() + 0xd1 bytes
WinSCPnet.dll!WinSCP.SessionLogReader.DoRead() + 0x64 bytes
WinSCPnet.dll!WinSCP.SessionLogReader.Read(WinSCP.LogReadFlags flags) + 0x86 bytes
WinSCPnet.dll!WinSCP.CustomLogReader.TryWaitForNonEmptyElement(string localName, WinSCP.LogReadFlags flags) + 0x5f bytes
WinSCPnet.dll!WinSCP.CustomLogReader.WaitForNonEmptyElement(string localName, WinSCP.LogReadFlags flags) + 0x29 bytes
WinSCPnet.dll!WinSCP.CustomLogReader.WaitForNonEmptyElementAndCreateLogReader(string localName, WinSCP.LogReadFlags flags) + 0x29 bytes
WinSCPnet.dll!WinSCP.Session.Open(WinSCP.SessionOptions sessionOptions) + 0x775 bytes

A first chance exception of type 'System.IO.IOException' occurred in mscorlib.dll

Additional information: The process cannot access the file 'C:\Users\Admin\AppData\Local\Temp\wscp24C0.0223CC89.tmp' because it is being used by another process.

private bool uploadFile(string path, string hostName, string username, string password)
{
    try
    {
        // Setup session options
        SessionOptions sessionOptions = new SessionOptions
        {
            Protocol = Protocol.Sftp,
            HostName = hostName,
            UserName = username,
            Password = password,
            SshHostKeyFingerprint = "ssh-rsa 1024 **:**:**:**:20:8f:95:69:12:f5:52:**:**:**:**:**"
        };
 
        using (Session session = new Session())
        {
            // Connect
            session.Open(sessionOptions);
 
            // Upload files
            TransferOptions transferOptions = new TransferOptions();
            transferOptions.TransferMode = TransferMode.Binary;
 
            TransferOperationResult transferResult;
            transferResult = session.PutFiles(path, "/", false, transferOptions);
 
            // Throw on any error
            transferResult.Check();
 
            // Print results
            foreach (TransferEventArgs transfer in transferResult.Transfers)
            {
                Console.WriteLine("Upload of {0} succeeded", transfer.FileName);
            }
        }
 
        return true;
    }
    catch (Exception e)
    {
        Console.WriteLine("Error: {0}", e);
        return false;
    }
}