How to fix the «TypeError: DateInterval::__construct() expects exactly 1 parameter, 2 given in magento/module-reward/Model/ResourceModel/Reward/History/Collection.php:288» Magento 2 Enterprise bug?

It is a bug in the Magento_Reward Magento 2 Enterprise module.
The problem method is \Magento\Reward\Model\ResourceModel\Reward\History\Collection::loadExpiredSoonPoints():

 * Return total amounts of points that will be expired soon (pre-configured days value) for specified website
 * Result is grouped by customer
 * @param int $websiteId Specified Website
 * @param bool $subscribedOnly Whether to load expired soon points only for subscribed customers
 * @return $this
public function loadExpiredSoonPoints($websiteId, $subscribedOnly = true)
	$expiryConfig = $this->_getExpiryConfig($websiteId);
	if (!$expiryConfig) {
		return $this;
	$inDays = (int)$expiryConfig->getExpiryDayBefore();
	// Empty Value disables notification
	if (!$inDays) {
		return $this;

	// join info about current balance and filter records by website

	$field = $expiryConfig->getExpiryCalculation() == 'static' ? 'expired_at_static' : 'expired_at_dynamic';
	$expireAtLimit = (new \DateTime(null, new \DateTimeZone('UTC')))
		->add(new \DateInterval('P', $inDays . 'D'))
		->format('Y-m-d H:i:s');

		['total_expired' => new \Zend_Db_Expr('SUM(points_delta-points_used)')]
		'points_delta-points_used > 0'
		"{$field} IS NOT NULL" // expire_at - BEFORE_DAYS < NOW
		// eq. expire_at - BEFORE_DAYS < NOW
		"{$field} < ?",
		['reward_table.customer_id', 'main_table.store_id']

	if ($subscribedOnly) {

	$this->setFlag('expired_soon_points_loaded', true);

	return $this;

Look at the block:

$expireAtLimit = (new \DateTime(null, new \DateTimeZone('UTC')))
	->add(new \DateInterval('P', $inDays . 'D'))
	->format('Y-m-d H:i:s');

It tries to create a DateInterval with 2 parameters.
Magento 2 Enterprise developers should learn PHP: the DateInterval::__construct() method accepts only 1 paramerer.

So to fix the issue you should contact the Magento 2 Enterprise support.