Error Log recurrente

[Eutanasio]

Buenas,

Tengo el error log del servidor lleno de este error recurrente que no sé a qué se debe:

[proxy_fcgi:error] [pid 3793974:tid 140607456519936] [client 41.249.77.211:0] AH01071: Got error 'PHP message: PHP Warning:  Invalid argument supplied for foreach() in /.../override/controllers/admin/AdminStatsController.php on line 594\n', referer: https://website/admin/index.php?controller=AdminOrders&token=xxxxx&submitFilterorder=1

El código de la línea 594 de dicho fichero es:

foreach ($orders as $order) {
            // Add flat fees for this order
            $flat_fees = Configuration::get('CONF_ORDER_FIXED') + (
                $order['id_currency'] == Configuration::get('PS_CURRENCY_DEFAULT')
                    ? Configuration::get('CONF_' . strtoupper($order['module']) . '_FIXED')
                    : Configuration::get('CONF_' . strtoupper($order['module']) . '_FIXED_FOREIGN')
                );

            // Add variable fees for this order
            $var_fees = $order['total_paid_tax_incl'] * (
                $order['id_currency'] == Configuration::get('PS_CURRENCY_DEFAULT')
                    ? Configuration::get('CONF_' . strtoupper($order['module']) . '_VAR')
                    : Configuration::get('CONF_' . strtoupper($order['module']) . '_VAR_FOREIGN')
                ) / 100;

            // Add shipping fees for this order
            $shipping_fees = $order['total_shipping_tax_excl'] * (
                $order['id_country'] == Configuration::get('PS_COUNTRY_DEFAULT')
                    ? Configuration::get('CONF_' . strtoupper($order['carrier_reference']) . '_SHIP')
                    : Configuration::get('CONF_' . strtoupper($order['carrier_reference']) . '_SHIP_OVERSEAS')
                ) / 100;

            // Tally up these fees
            if ($granularity == 'day') {
                if (!isset($expenses[strtotime($order['date'])])) {
                    $expenses[strtotime($order['date'])] = 0;
                }
                $expenses[strtotime($order['date'])] += $flat_fees + $var_fees + $shipping_fees;
            } else {
                $expenses += $flat_fees + $var_fees + $shipping_fees;
            }
        }

PS 1.7.6
Gracias por la ayuda!