You set a minimum order quantity of 6. You test it on the product page — it works. Then a customer adds 4 straight from the shop grid, and it lands in the cart with no warning. This is the single most common complaint about WooCommerce quantity plugins, and it is a design gap, not a bug you can configure away.
Where validation actually runs
WooCommerce fires woocommerce_add_to_cart_validation on every add-to-cart, everywhere. Many quantity plugins, though, only render their rules into the product-page quantity field via woocommerce_quantity_input_args. The shop grid’s “Add to Cart” button has no quantity field — it adds one unit, or whatever a theme’s AJAX handler passes — so a plugin that only touches the field never gets a say.
What “everywhere” needs to cover
- Single product page
- Shop / category archives and product carousels
- Classic cart quantity updates
- Block cart & block checkout (the Store API)
- The All Products block
How to fix it today
Either configure your shop “Add to Cart” buttons to link to the product page (so the quantity field is always in play), or use a plugin that validates on woocommerce_add_to_cart_validation and wires into the Store API for the block cart. That combination is what Quantity Manager was built for.
FAQ
Does linking shop buttons to the product page hurt conversion?
For products with quantity rules it usually helps — the customer sees the rule and the price table before they commit, instead of a checkout error.
Is this a theme problem or a plugin problem?
Both can contribute. A theme with a custom AJAX add-to-cart can bypass validation; a plugin that only edits the quantity field never enforces anything off the product page.