Add row to existing Datatable

Question

I want to add new row to existing datagridview. There is a problem beacause datagridview is connected to datasource and I can't add row by Rows.Add(). I have tried all commented lines and nothing works. Here is my code:

    private void SaveButton_Click(object sender, EventArgs e)
           {
            if (start_tab == start_picker.ToString("dd-MM-yyyy HH:mm:00") & stop_tab != stop_picker.ToString("dd-MM-yyyy HH:mm:00"))
            {
                DateTime new_starttime = stop_picker;
                DateTime new_stoptime = Convert.ToDateTime(stop_tab);
                int new_cycletime = Convert.ToInt32(dataGridView3.Rows[dataGridView3.CurrentRow.Index].Cells["cycle_time"].Value) - Convert.ToInt32(textBox32.Text);
                //devents.Rows.Add(new_starttime, new_stoptime, new_cycletime);
                //DataTable devents = new DataTable();
                //DataTable devents = 
                //DataRow newRow = devents.NewRow();
                //newRow["start_time"] = new_starttime;
                //newRow["stop_time"] = new_stoptime;
                //newRow["cycle_time"] = new_cycletime;
                //devents.Rows.Add(newRow);
                dataGridView3.Rows.RemoveAt(dataGridView3.CurrentCell.RowIndex);
                dataGridView3.Update();
                dataGridView3.Refresh();
          }
            }

Data to datagridView is loaded from another private void:

    private void Openbutton_Click(object sender, EventArgs e)
    {
        OpenReport();
        EventClass eventData = new EventClass();
        DataTable devents = eventData.Load_downtimes();
        dataGridView3.DataSource = devents;

Answer 1

Adding to the DataTable should actually work.
The question is how you got devents here, it is declared locally in Openbutton_Click below.
You can best get it directly from the dgv (must be cast because DataSource can have various types)

var devents = (DataTable)dataGridView3.DataSource;

DataRow newRow = devents.NewRow();
newRow["start_time"] = new_starttime;
newRow["stop_time"] = new_stoptime;
newRow["cycle_time"] = new_cycletime;
devents.Rows.Add(newRow);