While saving product throws "Unable to save Stock Item" exception in magento 2.2.6

Question

While saving product in backend,throws "Unable to save Stock Item".

I have tried after flushed the cache and reindexing but still exception throws.

I have reffered below link, but no luck

https://community.magento.com/t5/Magento-2-x-Technical-Issues/Cannot-add-products-in-Magento-2-1-11-quot-Unable-to-save-Stock/td-p/108369

In exception log throws

[2019-04-09 11:04:50] main.CRITICAL: Unable to save Stock Item {"exception":"[object] (Magento\Framework\Exception\CouldNotSaveException(code: 0): Unable to save Stock Item at /var/www/html/vega/vendor/magento/module-catalog-inventory/Model/Stock/StockItemRepository.php:183, Zend_Db_Statement_Exception(code: 23000): SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (vega.cataloginventory_stock_item, CONSTRAINT CATINV_STOCK_ITEM_STOCK_ID_CATINV_STOCK_STOCK_ID FOREIGN KEY (stock_id) REFERENCES cataloginventory_stock (stock_id) ON DELETE CASCADE), query was: INSERT INTO cataloginventory_stock_item (product_id, stock_id, qty, min_qty, use_config_min_qty, is_qty_decimal, backorders, use_config_backorders, min_sale_qty, use_config_min_sale_qty, max_sale_qty, use_config_max_sale_qty, is_in_stock, low_stock_date, notify_stock_qty, use_config_notify_stock_qty, manage_stock, use_config_manage_stock, stock_status_changed_auto, use_config_qty_increments, qty_increments, use_config_enable_qty_inc, enable_qty_increments, is_decimal_divided, website_id) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?) at /var/www/html/vega/vendor/magento/zendframework1/library/Zend/Db/Statement/Pdo.php:235, PDOException(code: 23000): SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (vega.cataloginventory_stock_item, CONSTRAINT CATINV_STOCK_ITEM_STOCK_ID_CATINV_STOCK_STOCK_ID FOREIGN KEY (stock_id) REFERENCES cataloginventory_stock (stock_id) ON DELETE CASCADE) at /var/www/html/vega/vendor/magento/zendframework1/library/Zend/Db/Statement/Pdo.php:228)"} []

Answer 1

catalog_inventory_stock have filled default data when installing magento. (ref : module-catalog-inventory/Setup/Patch/Data/CreateDefaultStock.php) And the script truncate cataloginventory_stock. So you need to fill default data manually like as below.

"INSERT INTO cataloginventory_stock (stock_id, website_id, stock_name) VALUES (1, 0, 'Default');"