Update Query throwing no error but records not getting updated using C#

Building queries with concatenation is poor and insecure way of nuilding queries. Please make use of parameterized querties. For more details refer Parameterized Queries ADO.Net

Also I have corrected your code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Configuration;
 
public partial class Default2 : System.Web.UI.Page
{
    SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
 
 
    protected void Page_Load(object sender, EventArgs e)
    {
        
        con.Open();
       Label1.Text = Request.QueryString["s"].ToString();
    }
 
else if (RadioButton3.Checked )
        {
           
            string z = "Voted";
            
             
 
            SqlCommand cmd2 = new SqlCommand("UPDATE [users] SET [Address] = @Address WHERE [ElectionId] = @ElectionId, con);
            cmd2.Parameters.AddWithValue("@Address", z);
            cmd2.Parameters.AddWithValue("@ElectionId", Label1.Text);
            cmd2.ExecuteNonQuery();
            con.Close();
        }
}
}