Fatal error: Uncaught Error: strtolower(): Argument #1 ($string) must be of type string, array given
in /var/www/wp-content/plugins/woocommerce/includes/wc-formatting-functions.php on line 24

Call stack:

1. strtolower()
   wp-content/plugins/woocommerce/includes/wc-formatting-functions.php:24
2. wc_string_to_bool()
   wp-content/plugins/woocommerce/includes/abstracts/abstract-wc-product.php:955
3. WC_Product::set_manage_stock()
   wp-content/plugins/woocommerce/includes/abstracts/abstract-wc-data.php:738
4. WC_Data::set_props()
   wp-content/plugins/woocommerce/includes/data-stores/class-wc-product-variation-data-store-cpt.php:375
5. WC_Product_Variation_Data_Store_CPT::read_product_data()
   wp-content/plugins/woocommerce/includes/data-stores/class-wc-product-variation-data-store-cpt.php:81
6. WC_Product_Variation_Data_Store_CPT::read()
   wp-content/plugins/woocommerce/includes/class-wc-data-store.php:159
7. WC_Data_Store::read()
   wp-content/plugins/woocommerce/includes/abstracts/abstract-wc-product.php:138
8. WC_Product::__construct()
   wp-content/plugins/woocommerce/includes/class-wc-product-simple.php:24
9. WC_Product_Simple::__construct()
   wp-content/plugins/woocommerce/includes/class-wc-product-variation.php:54
10. WC_Product_Variation::__construct()
    wp-content/plugins/woocommerce/includes/class-wc-product-factory.php:46
11. WC_Product_Factory::get_product()
    wp-content/plugins/woocommerce/includes/wc-product-functions.php:72
12. wc_get_product()
    wp-content/plugins/woocommerce/includes/data-stores/class-wc-product-variable-data-store-cpt.php:299
13. WC_Product_Variable_Data_Store_CPT::read_price_data()
    wp-content/plugins/woocommerce/includes/class-wc-data-store.php:224
14. WC_Data_Store::__call()
    wp-content/plugins/woocommerce/includes/class-wc-product-variable.php:81
15. WC_Product_Variable::get_variation_prices()
    wp-content/plugins/woocommerce/includes/class-wc-product-variable.php:492
16. WC_Product_Variable::is_on_sale()
    wp-content/plugins/woocommerce/includes/wc-template-functions.php:527
17. wc_product_post_class()
    wp-includes/class-wp-hook.php:308
18. WP_Hook::apply_filters()
    wp-includes/plugin.php:205
19. apply_filters()
    wp-includes/post-template.php:602
20. get_post_class()
    wp-includes/post-template.php:462
21. post_class()
    wp-content/themes/grappa/woocommerce/content-product.php:54
22. require()
    wp-includes/template.php:785
23. load_template()
    wp-content/plugins/woocommerce/includes/wc-core-functions.php:284
24. wc_get_template_part()
    wp-content/themes/grappa/functions.php:1641
25. grappaLoopProducts()
    wp-content/themes/grappa/woocommerce/taxonomy-product_cat.php:143
26. include()
    wp-includes/template-loader.php:106
27. require_once()
    wp-blog-header.php:19
28. require()
    index.php:17