Hi @alvin-leung-concept4, I'm unable to recreate the local behaviour without using the --experimental-require-module flag.

This functionality was initially introduced in Node.js versions 22.0.0 and 20.17.0 behind the --experimental-require-module flag. In later versions, specifically Node.js v23.0.0, the feature was no longer behind this flag, and in v23.5.0, the experimental warning associated with it was removed by default.

I'm digging more to find a solution for you. Will share here when I have a working example.

Hi @alvin-leung-concept4, I was able to run your code on Vercel Nodejs v22 by providing the flag in the NODE_OPTIONS environment variable using vercel.json:

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{
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  "env": {
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    "NODE_OPTIONS": "--experimental-require-module"
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  },
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  "rewrites": [{ "source": "/(.*)", "destination": "/api" }]
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}

I hope this solves your issue.

Thank you for your response.

I couldn't replicate your success. I have used your vercel.json, and it still doesn't work.

I see the flag --no-experimental-require-module in process.execArgv and it overrides the --experimental-require-module flag in NODE_OPTIONS. Not sure how your deployment has the opposite flag set.

Here is my result:

Oh, I see. I deployed using Vercel CLI. Did you deploy using Vercel CLI or the GitHub integration?

By the way, I had changed the project structure a little bit:

I have try deploying using both GitHub integration and Vercel CLI, and the deployments always have the flag --no-experimental-require-module set in process.execArgv.