If you are using a Vintage theme or your theme doesn’t let you place app blocks in the product section, you’ll need to add the custom fields code directly to your theme template.
Here’s how to do it:
- In your Shopify admin, go to Online Store > Themes.
- Find the theme you want to edit and click Actions > Edit code.
- Under the Templates header, open the product-template.liquid file.
- Decide where on the product page you want the custom fields to appear.
- Paste this code where you want the fields to show:
- Click Save.
This will add the custom fields to your product page even if your theme does not support app blocks.
Express checkout bypasses required fields
If you use required product page fields (personalization, terms checkbox, age verification, file upload), consider disabling dynamic checkout buttons (Apple Pay, Shop Pay, Google Pay) on products where those fields are mandatory. Customers using express checkout skip the product page entirely and go straight to checkout — they never see your required fields, so they can complete a purchase without providing the data you need. This is a platform limitation, not an app bug. In Shopify, you can disable dynamic checkout buttons per product or globally in your theme settings to ensure customers always pass through the product page and complete required fields.
Paid fields require published products
Paid fields (embroidery +$X, gift wrapping +$Y, rush fees) create hidden products behind the scenes. These products must be set to "Active" and available on your Online Store sales channel — they can be "Unlisted" so they don't appear in collections or search, but they must be published. If the paid add-on price doesn't show in the cart or the option doesn't work, this is almost always the cause. Check your Shopify admin: Products → find the generated add-on products → ensure Status is Active and the Online Store sales channel is enabled. This is the #1 setup mistake with paid fields.
Originally from our Help Center