A developer created their first checkout UI extension app targeting the purchase.checkout.contact.render-after location. The app worked locally but failed to load when deployed to their development store.
Root Cause:
Checkout UI extensions require a development store with Checkout and Customer Accounts Extensibility enabled. The developer’s store lacked this capability, which is only available on Shopify Plus plans and specific development store types.
Solution Steps:
Create a new development store through the Shopify Partner Dashboard
During setup, select the “Developer Preview” option (not “Current release”)
Choose the store type with Checkout and Customer Accounts Extensibility
Deploy the app using shopify app dev commands
Verify the app block appears in the checkout customization theme editor
Verification:
Check store type by navigating to Settings > Apps and sales channels > Develop apps. The store must show “Checkout and Customer Accounts Extensibility” to support checkout UI extensions.
The issue was resolved once the developer created a new development store with the correct extensibility type using the Developer Preview option.
Summarized with AI on November 7.
AI used: claude-sonnet-4-5-20250929.
I created my very first extensibility application using the checkout-ui. This will be custom/unlisted app. I have it targeting here, purchase.checkout.contact.render-after . I was able to get it working, locally. When I went to deploy it to the development store I set up, it’s not loading.
Apps that customize the information, shipping, and payment pages of the checkout, including checkouts from draft orders, are available only to Shopify Plus.
So is that why my app is not working on my development store, cause its a custom plan and not a Shopify Plus plan?
Hello @pmb88 , I already created this type of checkout-ui extensions app in local at the development store. Please check your store type of the development store, It must be the CHECKOUT EXTENSIBILITY STORE type when your create a store. For this you have to create a store from your partner dashboard. If your store having the checkout extensibility store type then do the steps below.
Please check the errors in your app if you have the errors in the local, run the app commands for the shopify app dev, and it will install it to your development store if not installed. Also you can deploy your different app version after install your app in the development store. After run dev commands you can see your app block at the theme customisation of the checkout.
Feel free to reach out if you have any questions or need assistance.
How can I check if it is an Extensibility Store Type? How can enable it if it’s not? When I go to Settings > Checkout, it looks like its using the extensibility checkout. I don’t see the block in app block at the theme customisation of the checkout. It just says “Customizing with app blocks is not available for this page. To customize branding, go to settings.”
If your development store is Checkout and Customer Accounts Extensibility then you can work with and develop with the checkout-ui extensions of the shopify. If your store is not having the extensibility of the checkout and customer accounts then you need to create a new development store with help of the partner dashboard of your shopify partner account. At the partner dashboard when you create a new store for the development purpose and for testing purpose then after it will ask in that to choose what type of the extensibility you want to add in your development store.
please see the screenshots below to create a development store with Checkout and Customer Accounts Extensibility.
Thank you! This did it. I created this dev store before, but the only difference was that I selected the ‘Current release’, rather than the ‘Developer Preview’. Didn’t think that I needed to use the Developer Preview option
