Concurrency Violation when updating gridview using dataadapter

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C#

DataGridView

Hi,

I am trying to update the gridview using the dataadapter and dataset, but when i click the save button after changing the data in the grid I get Concurrency Violation error.

The code is as follows

namespace app1
{
    public partial class Form1 : Form
    {
        MySql.Data.MySqlClient.MySqlConnection conn;
        MySqlDataAdapter adapter;
        DataSet ds;
     
       public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
        }

        public void radButton2_Click(object sender, EventArgs e)
        {
            string myConnectionString;           
            myConnectionString = "server=localhost;uid=root;" +
                "pwd=xxxx;database=ldis;";
            
            conn = new MySql.Data.MySqlClient.MySqlConnection(myConnectionString);
             try
             {
                 conn.Open();
             }
             catch (MySql.Data.MySqlClient.MySqlException ex)
             {
                 MessageBox.Show(ex.Message);
             }

             DataTable dtusers = new DataTable() ;
             dtusers = Getusers();
             radGridView2.DataSource = dtusers;
               conn.Close();             
        }

        private DataTable Getusers()
        {
            string query = "select userid,password,user_group,status,expiry from users";
            adapter = new MySqlDataAdapter(query, conn);  // adapter declaration
            ds = new DataSet();
            adapter.Fill(ds);
            
            adapter.UpdateCommand = new MySqlCommand(
            "UPDATE users SET  password=@password, user_group=@user_group,status=@status  WHERE userid=@userid;", conn);
            adapter.UpdateCommand.Parameters.Add("@userid", MySqlDbType.VarChar, 25, "userrid");
            adapter.UpdateCommand.Parameters.Add("@password", MySqlDbType.VarChar, 45, "password");
            adapter.UpdateCommand.Parameters.Add("@user_group", MySqlDbType.VarChar, 45, "user_group");
            adapter.UpdateCommand.Parameters.Add("@status", MySqlDbType.VarChar, 10, "status");      
            adapter.UpdateCommand.UpdatedRowSource = UpdateRowSource.None;

            return ds.Tables[0];
        }

        private void radButton1_Click(object sender, EventArgs e)
        {
            adapter.Update(ds);           
        }
    }
}

any help or suggestions will be appreciated, searched Google but it seems problem is something specific with my code.