Fatal error: Uncaught TypeError: Argument 1 passed to Magento\Catalog\Model\ProductRepository::prepareSku() must be of the type string, null given, called in /home3/fna/public_html/vendor/magento/module-catalog/Model/ProductRepository.php on line 856 and defined in /home3/fna/public_html/vendor/magento/module-catalog/Model/ProductRepository.php:866 Stack trace: #0 /home3/fna/public_html/vendor/magento/module-catalog/Model/ProductRepository.php(856): Magento\Catalog\Model\ProductRepository->prepareSku(NULL) #1 /home3/fna/public_html/vendor/magento/module-catalog/Model/ProductRepository.php(329): Magento\Catalog\Model\ProductRepository->saveProductInLocalCache(Object(Magento\Catalog\Model\Product\Interceptor), '70f219631131d9b...') #2 /home3/fna/public_html/vendor/magento/module-catalog/Model/ProductRepository.php(294): Magento\Catalog\Model\ProductRepository->cacheProduct('70f219631131d9b...', Object(Magento\Catalog\Model\Product\Interceptor)) #3 /home3/fna/public_html/generated/code/Magento/Catalog/Model/ProductRepository in /home3/fna/public_html/vendor/magento/module-catalog/Model/ProductRepository.php on line 866