SerialPort.Close() hangs the application by Vince Noga

A (very lame) workaround is to do the close in a new thread. I haven't tested trying to reopen the port and I'm not sure that it would be a good thing to do!

Another (very lame) workaround is to update the user-interface (UI) in a different thread. It should not be this difficult to collect data from a serial port and display it in the UI.

*** WARNING ***
This simple example is just that, a simple example. It does not prevent data loss from the serial port to the UI.
***************

        private AutoResetEvent are = new AutoResetEvent(false);
        private bool portOpen = false;
        private string serialData = "";

        private void button1_Click(object sender, EventArgs e)
        {
            if (!serialPort1.IsOpen)
            {
                try
                {
                    serialPort1.PortName = "COM1";
                    serialPort1.BaudRate = 9600;
                    serialPort1.DataBits = 7;
                    serialPort1.Parity = System.IO.Ports.Parity.Even;
                    serialPort1.StopBits = System.IO.Ports.StopBits.One;
                    serialPort1.Open();
                    portOpen = true;
                    Thread t = new Thread(new ThreadStart(MonitorPort));
                    t.IsBackground = true;
                    t.Start();
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK,
                        MessageBoxIcon.Error);
                }
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            if (serialPort1.IsOpen)
            {
                //Tell MonitorPort() to stop updating the UI
                portOpen = false;

                //Wait for MonitorPort() to signal that it's done
                are.WaitOne();

                serialPort1.Close();
            }
        }

        //Declare a method signature that can be Invoked
//        private delegate void UIUpdater(string s);
        private delegate void UIUpdater();

        //A method that has the same signature as UIUpdater()
//        private void UIUpdate(string s)
        private void UIUpdate()
        {
            textBox1.Text = serialData;
        }

        private void MonitorPort()
        {
            try
            {
                //All this thread does is write the serial data to the UI.
                //This simple example is not written to prevent data loss!
                while (portOpen)
                {
                    this.Invoke(new UIUpdater(UIUpdate));
                    Thread.Sleep(100);
                }
            }
            finally
            {
                //Signal that the thread is terminating
                are.Set();
            }
        }

        private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
        {
            //If continuous data from the device, application can hang when
         //SerialPort.Close() is called.
            //this.Invoke(new UIUpdater(UIUpdate),
            // new object[] { serialPort1.ReadExisting() });

            //Save the data to an object where .Invoke() is not required.
            //This simple example is not written to prevent data loss!
            serialData = serialPort1.ReadExisting();
        }

I'm confused. The Issue Status says "Closed (By Design)". If SerialPort->Close() is "Designed" to work this way then it should be renamed to:

SerialPort->HangApp(Intermittency=>50%).

It would have saved me days of debugging if it were named more appropiately.

Seriously, I know MS doesn't want to support "Legacy" serial devices (or anything not PnP) and wishes these devices would just go away, but there are a gazillion serial port devices still out there and manufacturers are still making new Serial Port based products which programmers still have to make apps for.

Unless MS can talk H/W Manufacturers out of making Serial devices, you gotta help us out.

So how do we get this Issue reopened?