System.NullReferenceException: Object reference not set to an instance of an object
  at System.Windows.Forms.XplatUIWin32.PaintEventStart (IntPtr handle, Boolean client) [0x00000] 
  at System.Windows.Forms.XplatUI.PaintEventStart (IntPtr handle, Boolean client) [0x00000] 
  at System.Windows.Forms.Form.WndProc (System.Windows.Forms.Message& m) [0x00000] 
  at System.Windows.Forms.Control+ControlNativeWindow.WndProc (System.Windows.Forms.Message& m) [0x00000] 
  at System.Windows.Forms.NativeWindow.WndProc (IntPtr hWnd, Msg msg, IntPtr wParam, IntPtr lParam) [0x00000] 
System.NullReferenceException: Object reference not set to an instance of an object
  at System.Windows.Forms.XplatUIWin32.PaintEventStart (IntPtr handle, Boolean client) [0x00000] 
  at System.Windows.Forms.XplatUI.PaintEventStart (IntPtr handle, Boolean client) [0x00000] 
  at System.Windows.Forms.Form.WndProc (System.Windows.Forms.Message& m) [0x00000] 
  at System.Windows.Forms.Control+ControlNativeWindow.WndProc (System.Windows.Forms.Message& m) [0x00000] 
  at System.Windows.Forms.NativeWindow.WndProc (IntPtr hWnd, Msg msg, IntPtr wParam, IntPtr lParam) [0x00000]