Ftpwebrequest upload empty file after windows 1903 update

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
              UploadFile("test.txt", Server & "/test.txt", User, PW)
    End Sub

    Public Sub UploadFile(ByVal _FileName As String, ByVal _UploadPath As String, ByVal _FTPUser As String, ByVal _FTPPass As String)

        Try
            Dim _FileInfo As New System.IO.FileInfo(_FileName)
            Dim _FtpWebRequest As System.Net.FtpWebRequest = CType(System.Net.FtpWebRequest.Create(New Uri(_UploadPath)), System.Net.FtpWebRequest)
            _FtpWebRequest.Credentials = New System.Net.NetworkCredential(_FTPUser, _FTPPass)
            _FtpWebRequest.EnableSsl = True
            _FtpWebRequest.KeepAlive = False
            _FtpWebRequest.Timeout = 15000
            _FtpWebRequest.Method = System.Net.WebRequestMethods.Ftp.UploadFile
            _FtpWebRequest.UseBinary = True
            _FtpWebRequest.ContentLength = _FileInfo.Length
            Dim buffLength As Integer = 2048
            Dim buff(buffLength - 1) As Byte
            Dim _FileStream As System.IO.FileStream = _FileInfo.OpenRead()
            Dim _Stream As System.IO.Stream = _FtpWebRequest.GetRequestStream()
            Dim contentLen As Integer = _FileStream.Read(buff, 0, buffLength)
            Application.DoEvents()
            Do While contentLen <> 0
                _Stream.Write(buff, 0, contentLen)
                contentLen = _FileStream.Read(buff, 0, buffLength)
            Loop
                   Catch ex As Exception
        End Try
    End Sub