C# 使用MySqlBackup.NET导出数据库时出现异常

我使用备份来备份MYSQL数据库

    private void button2_Click(object sender, EventArgs e)
    {
        string file = "D:\\backup.sql";
        //string conn = "server=localhost;user=root;pwd=qwerty;database=test;";
        String str = @"server=192.168.1.219;database=abc;userid=sha;password='123';";
        MySqlBackup mb = new MySqlBackup(str);
        mb.ExportInfo.FileName = file;
        mb.Export();
    }

我的堆栈跟踪如下-

A first chance exception of type 'System.NullReferenceException' occurred in MySqlBackup.dll
System.Transactions Critical: 0 : <TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Critical"><TraceIdentifier>http://msdn.microsoft.com/TraceCodes/System/ActivityTracing/2004/07/Reliability/Exception/Unhandled</TraceIdentifier><Description>Unhandled exception</Description><AppDomain>TestAppMysqlDBConnect.vshost.exe</AppDomain><Exception><ExceptionType>System.NullReferenceException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType><Message>Object reference not set to an instance of an object.</Message><StackTrace>   at MySql.Data.MySqlClient.MySqlBackup.ExportExecute()
   at MySql.Data.MySqlClient.MySqlBackup.Export()
   at TestAppMysqlDBConnect.Form1.button2_Click(Object sender, EventArgs e) in C:\Users\Shashika\Documents\Visual Studio 2010\Projects\TestAppMysqlDBConnect\TestAppMysqlDBConnect\Form1.cs:line 52
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   ..

MySqlBackup.dll中发生了类型为“System.NullReferenceException”的第一次意外异常
系统。关键事务：0:http://msdn.microsoft.com/TraceCodes/System/ActivityTracing/2004/07/Reliability/Exception/UnhandledUnhandled exceptionTestAppMysqlDBConnect.vshost.exeSystem.NullReferenceException，mscorlib，版本=4.0.0.0，区域性=neutral，PublicKeyToken=B77A5C561934E089对象引用未设置为对象的实例。在MySql.Data.MySqlClient.MySqlBackup.ExportExecute（）处
在MySql.Data.MySqlClient.MySqlBackup.Export（）处
在TestAppMysqlDBConnect.Form1.button2上，单击C:\Users\Shashika\Documents\Visual Studio 2010\Projects\TestAppMysqlDBConnect\TestAppMysqlDBConnect\Form1.cs中的（对象发送方，事件参数e）：第52行
在System.Windows.Forms.Control.OnClick（EventArgs e）中
..

但是有一个异常，is说有一个空引用异常。当我通过C#程序将数据传递到数据库时。它已成功插入，没有异常。只有当我试图通过C#程序备份数据库时，才会出现此异常。我使用了上面链接中的2个Dll文件。这些是— MySql.Data.dll MySqlBackup.dll

我无法解决这个例外。请帮忙

尝试使用此函数（不要忘记必须将MySqlBackup.dll添加到项目引用中）：

---

请包含堆栈跟踪的文本副本。它显示在右下角的框架中。@pst-我想我包括了它now@pst-抱歉迟到了。我想这就是你想要的。是吗？是的。这在这里不是很有用-但它确实显示异常来自MySqlBackup.Export中的某个地方（直接）。@pst-谢谢。我想我现在解决了。MySqlBackup.dll需要另一个名为Ionic.Zip的dll。我把它纳入了我的计划，问题就解决了。再次感谢你。因为你的评论有助于解决这个问题。

public void Backup()
    {
        try
        {
            // Backup...
            DateTime Time = DateTime.Now;
            year = Time.Year;
            month = Time.Month;
            day = Time.Day;
            hour = Time.Hour;
            minute = Time.Minute;
            second = Time.Second;
            millisecond = Time.Millisecond;

            //Save file to Path with the current date as a filename
            string path;
            path = txb_Path.Text + year + "-" + month + "-" + day + "--" + hour + "-" + minute + "-" + second + ".sql";
            string file = path;
            using (MySqlConnection conn = new MySqlConnection(connectionString))
            {
                using (MySqlCommand cmd = new MySqlCommand())
                {
                    using (MySqlBackup mb = new MySqlBackup(cmd))
                    {
                        cmd.Connection = conn;
                        conn.Open();
                        mb.ExportToFile(file);
                        conn.Close();
                    }
                }
            }
            //Done----
        }
        catch (Exception ex)
        {
            MessageBox.Show("Error , unable to backup!" + ex.Message);
        }
    }