Error in updating the grid data

protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
        {
            
            string username = GridView1.DataKeys[e.RowIndex].Values["Name"].ToString();//Index was out of range. Must be non-negative and less than the size of the collection Parameter name: index (this is error)
            TextBox Remarks = (TextBox)GridView1.Rows[e.RowIndex].FindControl("txtRemarks");
            string connStr = ConfigurationManager.ConnectionStrings["myConnectionString"].ConnectionString;
            SqlConnection con = new SqlConnection(connStr);
            
            con.Open();
            SqlCommand cmd = new SqlCommand("update gridsample set Remarks='" + Remarks.Text + "'where Name='" + username+"';", con);
            cmd.ExecuteNonQuery();
            con.Close();
            GridView1.EditIndex = -1;
            BindEmployeeDetails();
        }
    }