AGREGAR session_close();
a class-wc-shipping-oca.php

Inicio del php agregar 

<?php
error_reporting(0);
 
session_start();
if (session_status() === PHP_SESSION_ACTIVE) {
    session_write_close();
}
if ( ! defined( ‘ABSPATH’ ) ) {
exit;
}
 
/**
 * WC_Shipping_Oca class.
 *
 * @extends WC_Shipping_Method
 */