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Accepted
Iván Rodríguez
Asked: 2022-05-20 15:45:23 +0800 CST 2022-05-20 15:45:23 +0800 CST

Try/catch sometimes doesn't catch Win32Exception in OnClosing event (Failed to create window handle)

  • 772

I'm using Environment.Exit() in the OnClosing event to make sure no threads are zombied when I close my app, and it's fine, that works. The problem is that every now and then closing the app throws an exception that I can't control.

Unhandled exception of type 'System.ComponentModel.Win32Exception' in System.Windows.Forms.dll

Failed to create window handle.

I have tried to use Try/catch but it doesn't help, the exception keeps throwing.

Does anyone know how I can properly handle this situation?

This is the code that is giving me the problem:

public void OnClosing(FormClosingEventArgs e)
{

       if (MessageBox.Show("Desea cerrar el programa?", "Advertencia",
        MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.No)
       {
           e.Cancel = true;
           return;//no salir
       }
        
        try
        {
            Environment.Exit(Environment.ExitCode);//--> aquí se produce la excepción (Error al crear identificador de)
        }
        catch (System.ComponentModel.Win32Exception ex)
        {
            string message = "AppClose::OnClosing()-> " + ex.Message + " Error code: " + ex.ErrorCode;
            MessageBox.Show(message, "Advertencia", MessageBoxButtons.OK, MessageBoxIcon.Error);                
        }       
}

Thank you very much!!

c#

1 Answers

  1. Best Answer

    It is normal that you do not catch that exception, after all, the code on which you do tryit does not throw it. If we consult the documentation Environment.Exitwe see the following:

    exceptions

    SecurityException

    The caller does not have sufficient security permissions to perform this function.

    And it is logical. Why would it throw an exception with an error of creating windows a function that closes the system?

    Is there another part of your code that creates windows that is not inside the block try? My main suspect is the MessageBox, which is a window after all and is not in the block try, try doing this:

    public void OnClosing(FormClosingEventArgs e)
{
    try {
        if (MessageBox.Show("Desea cerrar el programa?", "Advertencia",
        MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.No)
        {
            e.Cancel = true;
            return;//no salir
        }

        Environment.Exit(Environment.ExitCode);
    }
    catch (System.ComponentModel.Win32Exception ex)
    {
        string message = "AppClose::OnClosing()-> " + ex.Message + " Error code: " + ex.ErrorCode;
        Console.WriteLine(message);
    }       
}
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