response.body?.cancel() of fetch causes unexpected behaviors in App Router

[akkadaska]

Link to the code that reproduces this issue

https://codesandbox.io/p/devbox/lucid-cohen-8r5tyq?workspaceId=cf95a29a-9e60-48fa-8cf5-0d217db0d3c6

To Reproduce

1. Build and start server (npm run build && npm run start)
2. Access /

Current vs. Expected behavior

Expected:

• The ReadableStream (response.body) is successfully cancelled.

Current:

• response.body?.cancel() does not resolve, causing the page to not return.
• Once response.body?.cancel() is called, the Next.js server does not terminate when Ctrl + C is pressed in the terminal.

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #1 SMP Fri Mar 29 23:14:13 UTC 2024
  Available memory (MB): 39993
  Available CPU cores: 20
Binaries:
  Node: 22.11.0
  npm: 10.9.0
  Yarn: 1.22.15
  pnpm: 9.10.0
Relevant Packages:
  next: 15.0.2 // Latest available version is detected (15.0.2).
  eslint-config-next: 15.0.2
  react: 19.0.0-rc-02c0e824-20241028
  react-dom: 19.0.0-rc-02c0e824-20241028
  typescript: 5.6.3
Next.js Config:
  output: N/A

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

Not sure

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

next start (local), Other (Deployed)

Additional context

Reproduced with not only Next.js v15.0.2 but also v14.2.17 at least.
I know the way to get only header or consume body in other way. This issue focuses on the bug with response.body.cancel.

[JesseKoldewijn]

Not sure what the surrounding situation is, but perhaps the use of an abortSignal could do the trick? Just a suggestion ofc ;)