404 Template Throws 500 Error when Using Middleware (v14.2.7)

[tjdunklee]

Link to the code that reproduces this issue

https://codesandbox.io/p/devbox/jolly-taussig-tzm55f

To Reproduce

1. View the repro CodeSandbox
2. Try to visit any page that has a invalid url
3. Notice the 500 error.

Current vs. Expected behavior

I would expect the custom 404 template to be displayed, instead a 500 error is thrown. This only seems to happen if a Middleware file is present. This seemed to start with v14.2.7.

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #1 SMP PREEMPT_DYNAMIC Sun Aug  6 20:05:33 UTC 2023
  Available memory (MB): 4102
  Available CPU cores: 2
Binaries:
  Node: 20.9.0
  npm: 9.8.1
  Yarn: 1.22.19
  pnpm: 8.10.2
Relevant Packages:
  next: 14.2.7 // Latest available version is detected (14.2.7).
  eslint-config-next: N/A
  react: 18.3.1
  react-dom: 18.3.1
  typescript: 5.1.3
Next.js Config:
  output: N/A

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

Middleware

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

next dev (local), next build (local), Other (Deployed)

Additional context

No response

[mauricedb]

Running into the same issue.
Another repro can be found here: https://github.com/mauricedb/next-pages-404

I can confirm this started with v14.2.7 and v14.2.6 works as expected.

Workaround for me
Adding a export const config with a matcher limiting the middleware to the known valid routes so the middleware doesn't execute on the route that causes the 404 errors.

[tjdunklee]

Thanks for the additional repro @mauricedb. Could you upvote 👍 my initial comment just to raise the visibility of this issue?

[ztanner]

Thanks for the report folks -- we're looking into this.

[tjdunklee]

Thanks for the update @ztanner! Much appreciated.

[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.