Adding a middleware causes additional requests to /_next/data/**/*.json and their reponses are empty {}.

[inside]

Link to the code that reproduces this issue

https://github.com/inside/repro-next-data-empty-object

To Reproduce

1. Clone this repo
2. npm install
3. npm run build
4. npm start
5. Open your browser to http://localhost:3000
6. Open the devtools
7. Go to the network tab
8. Notice each additional _next/data request for each link to a page

9. Click on either of the request
10. Click on the Response tab
11. Notice the empty json response like this {}

Current vs. Expected behavior

BUG:

When a middleware is active like this one: src/middleware.js, additional requests are made with an empty response {}.

A request url example looks like this: http://localhost:3000/_next/data/K-vmVE_c03yQwV9UdiOv2/page1.json and its reponse is empty {}.

EXPECTED BEHAVIOR:

No additional request should be performed. This is the case if you deactivate the middleware.

Verify canary release

• I verified that the issue exists in the latest Next.js canary release

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #99~20.04.1-Ubuntu SMP Thu Nov 2 15:16:47 UTC 2023
Binaries:
  Node: 20.10.0
  npm: 10.2.3
  Yarn: 1.22.21
  pnpm: 7.11.0
Relevant Packages:
  next: 14.0.4-canary.41
  eslint-config-next: 13.5.6
  react: 18.2.0
  react-dom: 18.2.0
  typescript: 5.3.2
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Middleware / Edge (API routes, runtime)

Additional context

If you access the url http://localhost:3000/_next/data/K-vmVE_c03yQwV9UdiOv2/page1.json directly in your browser, the page1 will be displayed like if we are accessing this url http://localhost:3000/page1

[warpdesign]

May already have been reported in #56157.
This appears to be intended?

[inside]

It probably is. Nevertheless this features has caused huge traffic and cpu spikes and we rolled back the activation of nextjs middlewares. Moreover these requests aren't cached which can explain the spikes:

In the meantime, we will deactivate the link prefetch of next/link to move forward.

[inside]

Hi, I've updated the reproduction repo with https://github.com/vercel/next.js/releases/tag/v14.1.1-canary.37 which contains the fix #60968 and I'm still encountering the issue.

[ijjk]

In the latest canary these requests are no-ops, they shouldn't cause CPU spikes or incur additional rendering/data fetching and further in the latest version these requests won't have an incorrect status code.

[github-actions]

This closed issue has been automatically locked because it had no new activity for 2 weeks. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.