[ERROR] Could not resolve "react-reconciler"

Extensions
,
1

Hi Team,
I am facing issue with “react-reconciler“ .
When install latest version of ui-extension package
npm install @shopify/ui-extensions@2025.7 @shopify/ui-extensions-react@2025.7
A new error raised like
✘ [ERROR] Could not resolve “react-reconciler”

2

Hey @Gutti_Yaswanth :waving_hand: - happy to help with this. I’m not certain how you’re building your package, but if you aren’t already using it, I’d recommend upgrading to API version 2025-10 with Preact. This is our officially recommended approach going forward and it should help eliminate the react-reconciler dependency problem you’re hitting.

Here’s the full upgrade guide for checkout UI extensions that walks through everything:

https://shopify.dev/docs/api/checkout-ui-extensions/latest/upgrading-to-2025-10

The upgrade is pretty straightforward though. You’d just need to update your shopify.extension.toml like this to use the new API version:

api_version = "2025-10"[[extensions]]name = "your-extension"handle = "your-extension"type = "ui_extension"# Contents of your existing file...

Then replace your dependencies in package.json with the Preact setup:

{  "dependencies": {    "preact": "^10.10.x",    "@preact/signals": "^2.3.x",    "@shopify/ui-extensions": "2025.10.x"  }}

You’ll also want to remove the old React packages:

npm uninstall react react-dom @shopify/ui-extensions-react react-reconciler @types/react

And install the new Preact ones:

npm install preact@^10.10.0 @preact/signals@^2.3.0 @shopify/ui-extensions@2025.10

After that, you’ll need to migrate your component code to use Preact and Polaris web components. The upgrade guide has examples showing the before and after for different patterns, including how to migrate checkout-specific hooks and API calls.

If you absolutely need to stay on version 2025.7, the workaround would likely be to manually install react-reconciler@0.29.0, but wanted to share our upgrade path as it will be the best path going forward

Let me know if you have any questions about the upgrade process or run into any issues. Happy to help if needed!