next.js: Next 13 fetch in server component stuck forever if response is larger than ~15kb

This hurts me deeply

Thanks for reporting, I did some digging, and the issue seems to be node-fetch-specific.

Currently, on the server, Next.js uses node-fetch to polyfill fetch when Node.js <18 is used. Above Node.js 18, or when the experimental: {enableUndici: true} option in next.config.js is present, we will use undici instead, which does not have this problem.

So current workarounds are:

1. Use Node.js 18 or above, if possible
2. Add the following to next.config.js:

module.exports = {
  experimental: {
    enableUndici: true
  }
}

Investigated this one on my flight back from Next.js Conf, it’s a known issue with cloning responses of fetch() in node-fetch and I could reproduce it with standalone node-fetch as well (outside of Next.js) both in the latest 2.x and 3.x release. Since we’re moving to using undici anyway I’ve made it so that appDir enabled it by default. Note that this does mean that appDir now requires Node.js 16.8 or later.

FYI, I just confirmed that this Vercel deployment aspect is fixed in v13.0.2-canary.1 via #42382

Hi this should be updated in v13.0.2 please update and give it a try!

FYI to @timneutkens, I can confirm that this is still broken when deploying to Vercel (same as what @icyJoseph is seeing). Neither manually setting enableUndici nor using next@13.0.2-canary.0 makes a difference.

Server Components that fetch large payloads hang until the serverless function times out.

I added some debug output and determined that my Vercel deployment is running Node.js v16.16.0.

When deploying to Vercel, on next@13.0.1, I still see this problem.

• The enableUndici flag is still needed, even locally though
• In Vercel, when the flag is active and with next@13.0.1, the build process goes swell, but then at runtime I get timeouts on functions that use fetch within Server Components. API routes work fine. Node version is the highest Vercel allows.

[GET] /pokemon/1
11:01:15:13
Fetching pokemon: 1
Got JSON for specie
2022-11-01T10:01:26.263Z 171204fd-e67e-4df5-8281-033e63eb019f Task timed out after 10.01 seconds

• This is the page
• Actual function

Could the problem be that this function lives at lib/ and not within app/? Locally all works wonderfully though.

Using Node 16.X ~

using node-fetch solved this

I can confirm it is fixed. Thanks!

module.exports = {
  experimental: {
    enableUndici: true
  }
}

enableUndici needs to be camelCase