Error "There is already an open DataReader associated with this Command which must be closed first" when using 2 distinct commands

Question

I have this legacy code :

 private void conecta()  {        if (conexao.State == ConnectionState.Closed)          conexao.Open();  }   public List<string[]> get_dados_historico_verificacao_email_WEB(string email)  {      List<string[]> historicos = new List<string[]>();      conecta();       sql =           @"SELECT *           FROM historico_verificacao_email           WHERE nm_email = '" + email + @"'           ORDER BY dt_verificacao_email DESC, hr_verificacao_email DESC";       com = new SqlCommand(sql, conexao);      SqlDataReader dr = com.ExecuteReader();       if (dr.HasRows)      {          while (dr.Read())          {              string[] dados_historico = new string[6];              dados_historico[0] = dr["nm_email"].ToString();              dados_historico[1] = dr["dt_verificacao_email"].ToString();              dados_historico[1] = dados_historico[1].Substring(0, 10);              dados_historico[2] = dr["hr_verificacao_email"].ToString();              dados_historico[3] = dr["ds_tipo_verificacao"].ToString();               sql =                   @"SELECT COUNT(e.cd_historico_verificacao_email) QT                   FROM emails_lidos e                   WHERE e.cd_historico_verificacao_email =                       '" + dr["cd_historico_verificacao_email"].ToString() + "'";               tipo_sql = "seleção";              conecta();              com2 = new SqlCommand(sql, conexao);               SqlDataReader dr3 = com2.ExecuteReader();              while (dr3.Read())              {                  //quantidade de emails lidos naquela verificação                  dados_historico[4] = dr3["QT"].ToString();               }              dr3.Close();              conexao.Close();               //login              dados_historico[5] = dr["cd_login_usuario"].ToString();              historicos.Add(dados_historico);          }          dr.Close();      }      else      {           dr.Close();      }       conexao.Close();      return historicos;  } 

I have created two separates commands to correct the issue, but it still continues: "There is already an open DataReader associated with this Command which must be closed first".

An additional info: the same code is working in another app.

Answer 1

Just add the following in your connection string:

MultipleActiveResultSets=True;