> ## Knowledge Base Index
> Fetch the complete knowledge base index at: https://docs.helixo.co/sitemap.xml
> Use this file to discover available pages before exploring further.
> Pure-Markdown content can be obtained by appending a '.md' suffix to the content URLs listed in the sitemap (without the trailing slash).

# Limitations of UFE

Almost 80% of the limitations of the Upsell Funnel Engine app are directly dependent on the limitations of [Shopify Draft Order](https://help.shopify.com/en/manual/orders/create-orders#set-item-or-order-discounts). [What is a Shopify draft order?](https://docs.helixo.co/en/article/what-is-a-shopify-draft-order-vdwyq7/) 

|| **Important**
|| **Upsell Funnel Engine** uses [Shopify Draft Order](https://help.shopify.com/en/manual/orders/create-orders#set-item-or-order-discounts) to apply discounts to the upsell/cross-sell offers if the widget has a **discount associated** with the UFE app.

## Limitations

* You can't use **multiple upsell apps** along with UFE
Learn more here:

  [Multiple upsell apps and theme support?](https://docs.helixo.co/en/article/multiple-upsell-apps-and-theme-support-ssffc7/)

* Some themes **show product pages quickly** while navigating from other pages (homepage or collection pages), this is done by pre-fetching the product details in the background, UFE doesn't support these cases.

* Some themes also use browser history API navigation to show pages quickly, **UFE doesn't support that!**

* May not work on some themes, but we do support almost all themes.
Learn more here:  

[Multiple upsell apps and theme support?](https://docs.helixo.co/en/article/multiple-upsell-apps-and-theme-support-ssffc7/)

* Don't work with quick view product display popups.

Hope you've got some value from this article. Let us know your feedback 🙂  We are excited to hear your thoughts.

|| **Did we miss something?**
|| No worries! Message us by clicking the chat icon 💬  inside the app.
|| Or Just email our team at [support@helixo.co](mailto:support@helixo.co) ✌️