C# Enable/disable user form when process exited event fires not working

Question

I have this code:

private void btnAddDataToCSV_Click(object sender, EventArgs e)
{
    var myProcess = new Process();
    this.Enabled = false;
    myProcess.EnableRaisingEvents = true;
    myProcess.Exited += new EventHandler(Excel_Exit);
    myProcess.StartInfo.FileName = "D:\\MyCsvFile.csv";
    myProcess.Start();     
}

public void Excel_Exit(object sender, System.EventArgs e)
{
    MessageBox.Show("Success!!");
    this.Enabled = true;
}

The code works as far as graying out all the buttons on my C# user form and opening the csv file in Excel. When I close Excel the exit event fires displaying a message "Success!!" But it doesn't re-enable the buttons after closing Excel.

I am getting the error

An unhandled exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll

on the this.Enabled = true; line.

As you can see from my comments below. I have now come to to realization that I cannot figure out how to disable even a single button.

private void btnAddDataToCSV_Click(object sender, EventArgs e)
{
    var myProcess = new Process();
    button1.Enabled = false;
    myProcess.EnableRaisingEvents = true;
    myProcess.Exited += new EventHandler(Excel_Exit);
    myProcess.StartInfo.FileName = "D:\\MyCsvFile.csv";
    myProcess.Start();     
}

public void Excel_Exit(object sender, System.EventArgs e)
{
    button1.Enabled = true;
}

The event is firing because the code below works... (displays success!!)

private void btnAddDataToCSV_Click(object sender, EventArgs e)
{
    var myProcess = new Process();
    myProcess.EnableRaisingEvents = true;
    myProcess.Exited += new EventHandler(Excel_Exit);
    myProcess.StartInfo.FileName = "D:\\MyCsvFile.csv";
    myProcess.Start();     
}

public void Excel_Exit(object sender, System.EventArgs e)
{
    MessageBox.Show("Success!!");
}

Any help would be greatly appreciated.

Answer 1

Replace this.Enabled = false; with AddtoCsv.Enabled = false;

private void btnAddDataToCSV_Click(object sender, EventArgs e)
            {
                var myProcess = new Process();
                AddtoCsv.Enabled = false;
                myProcess.EnableRaisingEvents = true;
                myProcess.Exited += new EventHandler(Excel_Exit);
                myProcess.StartInfo.FileName = "E:\\MyCsvFile.csv";
                myProcess.Start();
            }

Just call SetButtonStatemethod inside your Excel_Exit method, and do not forget to declare the delegate.

        public void Excel_Exit(object sender, System.EventArgs e)
        {
            
            // Set Button Enable State True
            SetButtonState();

        }

        private delegate void SafeCallDelegate();
        private void SetButtonState()
        {           

            // check if current thread is same which have created this control
            if (AddtoCsv.InvokeRequired)
            {
                SafeCallDelegate d = new SafeCallDelegate(SetButtonState);                
                AddtoCsv.Invoke(d);                
            }
            else
            {
                AddtoCsv.Enabled = true;
            }
        }

Answer 2

i have added 2 more controls to the form, and set it to disabled on opening of excel file.

private void btnAddDataToCSV_Click(object sender, EventArgs e)
        {
            var myProcess = new Process();
            AddtoCsv.Enabled = false;
            textBox1.Enabled = false;
            checkBox1.Enabled = false;
            myProcess.EnableRaisingEvents = true;
            myProcess.Exited += new EventHandler(Excel_Exit);
            myProcess.StartInfo.FileName = "E:\\MyCsvFile.csv";
            myProcess.Start();
        }

after that, fetched all the controls inside our form and pass it to SetButtonState method.

    public void Excel_Exit(object sender, System.EventArgs e)
    {

        // Set Button Enable State True
        var controls = this.Controls.Cast<Control>();

        foreach (Control ctrl in controls)
        {
            SetButtonState(ctrl);
        }
        
        
    }

SetButtonState wil make call to invoke method of passed control and then we are able to make changes onto control.

    private delegate void SafeCallDelegate(Control control);
    private void SetButtonState(Control control)
    {           

        // check if current thread is same which have created this control
        if (control.InvokeRequired)
        {
            SafeCallDelegate d = new SafeCallDelegate(SetButtonState);
            control.Invoke(d, control);                
        }
        else
        {
            control.Enabled = true;                                       
            
        }
    }

Answer 3

Ok... I couldn't get the entire form to disable. But based on other stuff I have found, I created a "panel" and put all my buttons inside the panel and was able to enable the entire panel.

So the solution below works. Special thanks to Paramjot Singh who posted the other solution which works great for a single button, I don't know if I would have figured this out without his help!!

private void btnAddDataToCSV_Click(object sender, EventArgs e)
{
    var myProcess = new Process();
    panel1.Enabled = false;
    myProcess.EnableRaisingEvents = true;
    myProcess.Exited += new EventHandler(Excel_Exit);
    myProcess.StartInfo.FileName = "E:\\MyCsvFile.csv";
    myProcess.Start();
}

public void Excel_Exit(object sender, System.EventArgs e)
{
        
    // Set Button Enable State True
    SetButtonState();

}

private delegate void SafeCallDelegate();
private void SetButtonState()
{           

    // check if current thread is same which have created this control
    if (panel1.InvokeRequired)
    {
        SafeCallDelegate d = new SafeCallDelegate(SetButtonState);                
        panel1.Invoke(d);                
    }
    else
    {
        panel1.Enabled = true;
    }
}