Fatal error: Uncaught TypeError: Argument 1 passed to Magento\Catalog\Model\ProductRepository::prepareSku() must be of the type string, null given, called in /var/www/clients/client1/web1/web/vendor/magento/module-catalog/Model/ProductRepository.php on line 790 and defined in /var/www/clients/client1/web1/web/vendor/magento/module-catalog/Model/ProductRepository.php:800 Stack trace: #0 /var/www/clients/client1/web1/web/vendor/magento/module-catalog/Model/ProductRepository.php(790): Magento\Catalog\Model\ProductRepository->prepareSku(NULL) #1 /var/www/clients/client1/web1/web/vendor/magento/module-catalog/Model/ProductRepository.php(349): Magento\Catalog\Model\ProductRepository->saveProductInLocalCache(Object(Magento\Catalog\Model\Product\Interceptor), '70f219631131d9b...') #2 /var/www/clients/client1/web1/web/vendor/magento/module-catalog/Model/ProductRepository.php(314): Magento\Catalog\Model\ProductRepository->cacheProduct('70f219631131d9b...', Object(Magento\Catalog\Model\Product\Interceptor)) #3 /var/www/clients/clien in /var/www/clients/client1/web1/web/vendor/magento/module-catalog/Model/ProductRepository.php on line 800