til/nextjs/fetch-does-not-work-in-api-serverless-function.md

Fetch Does Not Work In API Serverless Function

Next.js ships with its own implementation of fetch that extends the native fetch API.

I ran into a bug recently that was only reproducible in production. I had a Next.js API function that was POSTing to another API endpoint using fetch. I tested it several ways in development. It worked great. However, once the feature was in production, it was silently failing. After some console.log debugging, I discovered that the target API was getting an empty body in the POST request.

I don't know the specifics of why, but somehow the fetch implementation running in the Vercel serverless function environment apparently strips out the body of a POST request.

The solution, for me, was to add the node-fetch package and import that version of fetch in my API function. Once I made that change, my feature was working again.

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