MainWindow' does not contain a definition for 'Button_Click'

using System.Windows;
using System.Windows.Input;
using NHotkey.Wpf;
using NHotkey;

namespace EpicUnfriender
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();;
        }
        // StartButton
        public void Button_Click(object sender, RoutedEventArgs e){}
    }
}