Open file dialog freezes the program when I try to use it

Question

I am using visual studio 2017 to create a windows form application, which I am trying to use OpenFileDialog to load an XML file. When I first created the program everything works fine but after working and testing my code the application freezes when I launch the event to show the dialog.

I had this problem before where I was using Visual Studio 2015 and I could not find a solution.

public Form1()
{
    InitializeComponent();
}
    
private void btnLoad_Click(object sender, EventArgs e)
{
    if (ofdLoadXMLFile.ShowDialog() == DialogResult.OK)
    {
        string fileName = ofdLoadXMLFile.SafeFileName;
                
        MessageBox.Show(fileName);

        lblFileName.Text = fileName;
        File.Copy(ofdLoadXMLFile.FileName, fileName);

        XmlDocument document = new XmlDocument();
        string _byteOrderMarkUtf8 = Encoding.UTF8.GetString(Encoding.UTF8.GetPreamble());

        document.LoadXml(fileName.ToString());

        string jsonText = JsonConvert.SerializeXmlNode(document);
        string result = document.ToString();

        File.WriteAllText(@"C:\Users\Connect To All\Desktop\result.json", jsonText);
    }
}