Scaffold App Fails Generate Product Request With 400

Shopify CLI and Libraries
1

I have reproduced the issue on the latest CLI version.

Yes, I am on the latest version

I have searched existing posts and this report is not a duplicate.

Yes, this isn’t a duplicate

In which of these areas are you experiencing a problem?

App

Expected behavior

The scaffolded app should successfully send a generate product request.

Actual behavior

Running the CLI init command then following the instructions on your page to start the dev app should work before any code is changed, but it doesn’t even reach the react router backend, failing on a 400 Bad Request.

Reproduction steps

Follow the steps here: Scaffold an app
I’m on the most recent version as of right now: @shopify/cli 4.7.1

Verbose output

16:44:17 │ React Router │ at singleFetchAction
(file:///C:/Users/bronc/Dev/bmd-custom-product-previewer/node_modules/.pnpm/react-router@7.18.3_react-d_1ad31ebd059bdeff8ab250ef9dbbfe81/node_modules/react-router/dist/development/chunk-HT4INDD5.mjs:866:31)
16:44:17 │ React Router │ at handleSingleFetchRequest
(file:///C:/Users/bronc/Dev/bmd-custom-product-previewer/node_modules/.pnpm/react-router@7.18.3_react-d_1ad31ebd059bdeff8ab250ef9dbbfe81/node_modules/react-router/dist/development/chunk-HT4INDD5.mjs:1403:59)
16:44:17 │ React Router │ at requestHandler
(file:///C:/Users/bronc/Dev/bmd-custom-product-previewer/node_modules/.pnpm/react-router@7.18.3_react-d_1ad31ebd059bdeff8ab250ef9dbbfe81/node_modules/react-router/dist/development/chunk-HT4INDD5.mjs:1245:24)
16:44:17 │ React Router │ at requestHandler
(file:///C:/Users/bronc/Dev/bmd-custom-product-previewer/node_modules/.pnpm/react-router@7.18.3_react-d_1ad31ebd059bdeff8ab250ef9dbbfe81/node_modules/react-router/dist/development/chunk-HT4INDD5.mjs:1349:12)
16:44:17 │ React Router │ at nodeHandler
(C:\Users\bronc\Dev\bmd-custom-product-previewer\node_modules.pnpm@react-router+dev@7.18.3_@r_2ef7e417aa46323f2d25eb6d15200b16\node_modules@react-router\dev\dist\vite.js:3889:36)
16:44:17 │ React Router │ at C:\Users\bronc\Dev\bmd-custom-product-previewer\node_modules.pnpm@react-router+dev@7.18.3_@r_2ef7e417aa46323f2d25eb6d15200b16\node_modules@react-router\dev\dist\vite.js:3896:17

Operating system

I tried this on both Windows 10 and MacOS 26.6.2 (Tahoe)

CLI version

4.7.1

Shell

zsh

Nodejs version

24.17.0

What language and version are you using in your application?

Node 24.17.0

2

I was able to workaround the issue by creating a react-router.config.ts file and adding: allowedActionOrigins: [“*.trycloudflare.com”]. I also tested this using both the react router useFetcher (which the scaffold generates) and the fetch API. Both were able to reach the react router action on the localhost server after adding this configuration.

4

Hi @BMD_dev, thanks for flagging this. Looks like this issue popped up with the recent React Router version (7.18.3). This is being looked into now.