Doctrine\ORM\ORMInvalidArgumentException: A new entity was found through the relationship \app\Entity\Shop#ShopImage that was not configured to cascade persist operations for entity: app\Entity\Shop\ShopImage@7139. 
To solve this issue: Either explicitly call EntityManager#persist() on this unknown entity or configure cascade persist this association in the mapping, for example, @ManyToOne(..,cascade={"persist"}).

$this->filterImageNeedToDeleteS3($ShopTmp->getShopImageTmp(), $Shop->getShopImage());
$this->deleteShopImages($Shop);

foreach ($ShopTmp->getShopImageTmp() as $ShopImageTmp) {
      if ($ShopImageTmp->getFileName()) {
              $ShopImage = new ShopImage();
              $ShopImage->setShop($Shop);
              $ShopImage->setFileName($ShopImageTmp->getFileName());
              $this->entityManager->persist($ShopImage);
              $this->entityManager->flush();
      }
}

if (count($ShopTmp->getShopImageTmp()) < 1) {
        $ShopImage = new ShopImage();
        $ShopImage->setShop($Shop);
        $ShopImage->setFileName(null);
        $this->entityManager->persist($ShopImage);
        $this->entityManager->flush();
}

 /**
   * @ORM\ManyToOne(targetEntity="app\Entity\Shop", inversedBy="ShopImage", cascade={"persist"})
   * @ORM\JoinColumn(name="shop_id", referencedColumnName="id", onDelete="CASCADE")
   * @ORM\OrderBy({
   *     "sort_no"="ASC"
   * })
   */
   private $Shop;

// Old code

$ShopImages = $this->shopImageRepository->findBy([
            'Shop' => $Shop,
]);

 foreach ($ShopImages as $ShopImage) {
      $this->entityManager->remove($ShopImage);
 }

// New code
 $this->shopImageRepository
         ->createQueryBuilder('s')
         ->delete()
         ->where("s.Shop= :Shop")
         ->setParameter('Shop', $Shop)
         ->getQuery()
         ->execute()
 ;