Magento 2 – How to Get Order Increment ID Using Order ID

I had the same issue. Modifying the sales_sequence_profile table worked for me in Magento 2.1.1.

#mysql - I'm changing prefix for everything here - add where condition if you only want to update order prefix
update sales_sequence_profile set prefix = 6

# Magento command line
bin/magento cache:flush
bin/magento indexer:reindex

Magento 2 uses Service Contracts for retrieving and saving objects. In Magento this layer is formed by Repositories, which are managers with get() and save() methods. This keeps user code away from Model calls. Don't call model methods (like load() or save() or loadByIncrementId()) directly, they are being deprecated as custom code should use the Service Contracts. Also, don't use the API from within Magento like Khoa is suggesting, it does not make sense. The API is for connecting Magento with other systems.

Inject OrderRepository and SearchCriteriaBuilder in your constructor:

private $orderRepository;
private $searchCriteriaBuilder;

public function __construct(
        \Magento\Framework\App\Helper\Context $context,
        \Magento\Sales\Model\OrderRepository $orderRepository,
        \Magento\Framework\Api\SearchCriteriaBuilder $searchCriteriaBuilder
){
$this->orderRepository = $orderRepository;
$this->searchCriteriaBuilder = $searchCriteriaBuilder;
parent::__construct($context);
}

And in your function:

$searchCriteria = $this->searchCriteriaBuilder
    ->addFilter('increment_id', '000000001', 'eq')->create();
$orderList = $this->orderRepository->getList($searchCriteria)->getItems();

// $orderList is now an array of Orders with this incrementId, which is just one order obviously

/** @var \Magento\Sales\Model\Order $order */
$order = reset($orderList);
// Your logic here
$order = $this->orderRepository->save($order);

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