I have the same problem. With PHP 5.6 I get the following error:
wp-content/plugins/woo-mercado-pago-module/mercadopago/mercadopago-gateway.php on line 1367
and with PFP 7.0.18 or 7.1 I get this:
Fatal error: Uncaught Error: Call to a member function get_cart() on null in /home/aromboli/public_html/explora/wp-content/plugins/woo-mercado-pago-module/mercadopago/mercadopago-gateway.php:1367 Stack trace: #0 /home/aromboli/public_html/explora/wp-content/plugins/woocommerce/includes/class-wc-payment-gateways.php(154): WC_WooMercadoPago_Gateway->is_available() #1 /home/aromboli/public_html/explora/wp-content/plugins/woocommerce-subscriptions/includes/gateways/class-wc-subscriptions-payment-gateways.php(108): WC_Payment_Gateways->get_available_payment_gateways() #2 /home/aromboli/public_html/explora/wp-content/plugins/woocommerce-subscriptions/includes/admin/class-wc-subscriptions-admin.php(1531): WC_Subscriptions_Payment_Gateways::one_gateway_supports('subscriptions') #3 /home/aromboli/public_html/explora/wp-includes/class-wp-hook.php(298): WC_Subscriptions_Admin::add_recurring_payment_gateway_information(Array) #4 /home/aromboli/public_html/explora/wp-includes/plugin.php(203): WP_Hook->apply_filters(Array, Array) #5 /h in /home/aromboli/public_html/explora/wp-content/plugins/woo-mercado-pago-module/mercadopago/mercadopago-gateway.php on line 1367
Any idea on how to fix this?