Magento – Add multiple products to cart programatically – magento 2.1

The Fatal error: Maximum function nesting level of '200' reached, aborting! is caused by the fact that you are running into an endless loop.

Your action of $cart->save() is initiating your own routine, which is then action again, saving the cart, and then action your routine again etc....

To block this, you can check the cart items first, and determine if the item being injected is already in cart, and then simply exit the routine if so.

I faced same error while placing order programatically.

I have made some changes in your createOrder() function.

public function createOrder(Subscriptions $subscription, $originalOrder, $originalOrderItemId) {
        /**
         * @var $originalOrder \Magento\Sales\Model\Order
         * @var $quote         \Magento\Quote\Model\Quote
         * @var $customer
         */
        // Firstly make sure we can load the customer
        $customerId = $originalOrder->getCustomerId();
        //$customer = $this->_customerFactory->create()->load($customerId);
        $customer = $this->_customerInterface->getById($customerId);
        if ($customer->getEmail()) {
            // Get some data from the original order that we are going to need
            // @todo : load isn't deprecated it might be later
            $originalStoreId = $originalOrder->getStoreId();
            $store = $this->_store->load($originalStoreId);
            // Create a blank quote
            $quote = $this->_quoteFactory->create()->setStoreId($originalStoreId);

            /**
             * Added by Jaimin
             */
            $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
            $quoteRepository = $objectManager->create(\Magento\Quote\Api\CartRepositoryInterface::class);
            $quoteRepository->save($quote);
            /**
             * End
             */
            // Assign the customer to the quote
            $quote->assignCustomer($customer);
            //@todo : fix error with below - must implement interface Magento\Quote\Api\Data\CurrencyInterface
            //$currency = $originalOrder->getBaseCurrencyCode();
            //$quote->setCurrency($currency);
            //temporary - currency needs to be the purchased currency
            $quote->setCurrency();
            // Build Billing Address
            $billingAddress = clone $originalOrder->getBillingAddress();
            $billingAddress->unsetData('entity_id')->unsetData('parent_id')
                    ->unsetData('customer_address_id')->unsetData('customer_id')
                    ->unsetData('quote_address_id');
            // Build Shipping Address
            // @todo : Customers are going to need the ability to change their shipping address come back and fix this once that's done
            $shippingAddress = clone $originalOrder->getShippingAddress();
            $shippingAddress->unsetData('entity_id');
            // Insert the address details
            $quote->getBillingAddress()->addData($billingAddress->getData());
            $quote->getShippingAddress()->addData($shippingAddress->getData());
            /**
             * @var $subscriptionOrderItem \Magento\Sales\Model\Order\Item
             */
            // Load the subscription product from original order
            $subscriptionOrderItem = $originalOrder->getItemById(
                    $originalOrderItemId
            );
            // Make sure we have a product
            if ($subscriptionOrderItem instanceof SalesOrderItem) {
                // Get params required to add product
                $params = $this->getProductParams($subscriptionOrderItem);
                // Load the product
                $product = $this->getSubscriptionProduct(
                        $subscriptionOrderItem, $originalStoreId
                );
                // Product may have been deleted
                if (!$product) {
                    $message = sprintf(
                            __('Could not load product id %s for subscription %s'), $subscription->getProductId(), $subscription->getId()
                    );
                    $this->_logger->critical($message);
                    throw new LocalizedException($message);
                }
                //$quote->addProduct($product, $params);
                $this->_quoteInitializer->init($quote, $product, $params);
                // Set the product price based on original order incase product price changed
                try {
                    $this->setProductPrices(
                            $quote, $product, $subscription->getProductCost()
                    );
                } catch (LocalizedException $e) {
                    $message = __(
                            'Unable set custom price - cannot release subscription'
                    );
                    $this->_logger->critical($message);
                    throw new LocalizedException($message, $e);
                }
                $quote->setTotalsCollectedFlag(false)->collectTotals();
            } else {
                $message = __(
                                'Could not load original order item for subscription : '
                        ) . $subscription->getId();
                $this->_logger->critical($message);
                throw new LocalizedException(__($message));
            }
            // Collect shipping rates
            $quote->getShippingAddress()->setCollectShippingRates(true)
                    ->collectShippingRates();
            // Apply the correct shipping rate to this order
            $this->getShippingRate($quote, $originalOrder);
            // Set payment method - work still to be done here
            $quote->setPaymentMethod($this->_getPaymentMethod());
            // Create the quote

            /**
             * Change by Jaimin
             */
            //$quote->save();

            /**
             * End
             */
            // Import payment data - Don't understand this yet
            $quote->getPayment()->importData(
                    array('method' => $this->_getPaymentMethod())
            );
            // Collect quote totals
            $quote->collectTotals()->save();
            /**
             * @var $order \Magento\Sales\Model\Order
             */
            // Convert the quote to an order
            //$order = $this->_quoteManagement->submit($quote);

            /**
             * Added by Jaimin
             */
            $quoteManagement = $objectManager->create(\Magento\Quote\Api\CartManagementInterface::class);
            $quote = $quoteRepository->get($quote->getId());
            $order = $quoteManagement->submit($quote);
            /**
             * End
             */
            // Prevent default order confirmation, we will make our own
            $order->setEmailSent(0);
            // Make sure the order has been created properly
            if (!$order->getRealOrderId()) {
                $order = false;
            }
            $this->_logger->info(
                    sprintf(
                            __('Order %s succesfully created for subscription %s'), $order->getRealOrderId(), $subscription->getId()
                    )
            );
            return $order;
        } else {
            $message = __('The customer no longer exists for subscription: ')
                    . $subscription->getId();
            $this->_logger->critical($message);
            throw new LocalizedException(__($message));
        }
    }