Can not add coupon to product

-- HikaShop version -- : 4,2,3
-- PHP version -- : 7,2

We use coupon for product (free shipping)and when I want to add product to coupon wont save. We have some 50 product listed on that coupon. Now I can not add any new product. I can select, but when I save, product is missing.

Thank you. All clear.

Is there a way to limit shipping metod to that coupon?
We have free delivery for new products (we manage this manualy and it is ok). We use that coupon (limited to products and now to category) to give customer automatic coupon for delivery cost. But on checkout is that visible as coupon in the end, but delivery is still stated as some cost.
Sorry for my english, hope I explain ok.

nicolas wrote: Hi,

That's because of the size of the column in the database. You can open the hikashop_discount table via your phpmyadmin and edit the column discount_product_id and change its type to text instead of varchar and you'll be able to enter thousands of products in a coupon.

However, I would rather recommend to create an unpublished category and select it in the coupon.
Then, you can just add that category as a second category in the products for which you want the coupon to apply.

OK, thank you.