C#

private void Callbutton_Click(object sender, RoutedEventArgs e) 
{  
 tab.AddPresetmenu("CALL BUTTON");         
}

ObservableCollection<DataItem> items = new ObservableCollection<DataItem>(); 
public  void AddPresetmenu(string pMenu) 
        {  
            items.Add(new DataItem(pMenu)); 
            menubox.ItemsSource = items; 
            menubox.UpdateLayout();
        }

<ListBox x:Name="menubox" ItemsSource='{Binding}' Margin="0,5,0,0" Background="Silver" BorderThickness="0">                <br />
<ListBox.ItemTemplate><DataTemplate><br />
TextBlock Foreground="Blue" FontWeight="Bold" Text="{Binding Path=Name}" TextWrapping="Wrap"<br />
VerticalAlignment="Center"/><br />
 </DataTemplate><br />
 </ListBox.ItemTemplate><br />
 </ListBox>

for(int i = 0; i<AnimalsDataGridView.Rows.Count; i++)
{
   try
   {
    if (File.Exists(AnimalsDataGridView.Rows[i].Cells[4].Value.ToString()))
    {
      //get the filePath
      String currentPath = AnimalsDataGridView.Rows[i].Cells[4].Value.ToString();
      Image img = Image.FromFile(currentPath);
                        
      Image thumbnail = SetThumbnail(img, 200, 200);

      //get the title of the image and store in imageTitle variable
                        
       //save image to byte array
       byte[] imageInfo = ImageToByteArray(thumbnail);
                        
       //Primary key of the database. I have not enabled the autogeneration feature regarding this.
        Guid guid = getGuid(thumbnail);

       this.ZooTableAdapter.Update(guid, imageTitle, imageInfo, currentPath, guid);
       this.ZooTableAdapter.Fill(ZooDataSet.Animals);
    }
                    
  }
  catch (Exception e)
  {
    Console.WriteLine(e.Message.ToString());
  }
}

if (File.Exists(AnimalsDataGridView.Rows[i].Cells[4].Value.ToString()))

NullReference Exception was unhandled
Object reference not set to an instance of an object.

UPDATE [Animals] SET [Id] = @p1, [Title] = @p2, [Thumbnail] = @p3, [FullPath] = @p4 WHERE (([Id] = @p5))

private void SaveNativeBinary(string file, long origin, long length, string opt)
        {
            SetSSVisible(StatusStrip, pbSmallPerc, true);

            FileStream fs = null;
            FileStream writer = null;

            try { fs = new FileStream(file, FileMode.Open, FileAccess.Read); }
            catch { throw new Exception("ERR"); }

            try { writer = new FileStream(opt, FileMode.Create, FileAccess.ReadWrite); }
            catch { throw new Exception("ERR"); }

            fs.Seek(origin, SeekOrigin.Begin);


            for (long pos = 0; pos < length; pos++)
            {
                if (pos % 204800 == 0) // 200KB'da bir güncelle
                {
                    SetSSValue(StatusStrip, pbSmallPerc, Convert.ToInt32(PercentageCalc(pos, length)) );
                    SetSSText(StatusStrip, lblStatus, "Aktarılıyor: " + BtoKB(pos).ToString() + " / " + BtoKB(length).ToString() + " KB (%" + PercentageCalc(pos, length) + ")");
                }
                writer.WriteByte((byte)fs.ReadByte());
            }

            fs.Close(); fs.Dispose(); writer.Close(); writer.Dispose();
            SetSSVisible(StatusStrip, pbSmallPerc, false);
        }

private void AppendBinToBin(string Container, string toAppend)
        {
            SetSSVisible(StatusStrip, pbSmallPerc, true);
            FileStream fsA, fsB = null;
            long tempLength = GetFileLength(toAppend);

            try { fsA = new FileStream(Container, FileMode.Open, FileAccess.ReadWrite); }
            catch { throw new Exception("ERR"); }

            try { fsB = new FileStream(toAppend, FileMode.Open, FileAccess.Read); }
            catch { throw new Exception("RRR"); }

            try
            {
                fsA.Seek(0, SeekOrigin.End);
                for (long pos = 0; pos < fsB.Length; pos++)
                {
                    if (pos % 204800 == 0) // 200KB'da bir güncelle
                    {
                        SetSSValue( StatusStrip, pbSmallPerc, Convert.ToInt32(PercentageCalc(pos, tempLength)) );
                        SetSSText( StatusStrip, lblStatus, "Aktarılıyor: " + BtoKB(pos).ToString() + " / " + BtoKB(tempLength).ToString() + " KB (%" + PercentageCalc(pos, tempLength) + ")" );
                    }
                    fsA.WriteByte( (byte)fsB.ReadByte() );
                }
                fsB.Close(); fsB.Dispose(); fsA.Close(); fsA.Dispose();
            }
            catch { throw new Exception("ERR."); }
            SetSSVisible(StatusStrip, pbSmallPerc, false);
        }