custom server breaks during ssr prepass in 13.4

[juliusmarminge]

Verify canary release

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

Provide environment information

Operating System:
      Platform: darwin
      Arch: arm64
      Version: Darwin Kernel Version 22.4.0: Mon Mar  6 20:59:28 PST 2023; root:xnu-8796.101.5~3/RELEASE_ARM64_T6000
    Binaries:
      Node: 18.16.0
      npm: 9.5.1
      Yarn: N/A
      pnpm: 8.4.0
    Relevant packages:
      next: 13.4.0
      eslint-config-next: 13.3.4
      react: 18.2.0
      react-dom: 18.2.0

Which area(s) of Next.js are affected? (leave empty if unsure)

No response

Link to the code that reproduces this issue

https://github.com/trpc/examples-next-prisma-websockets-starter

To Reproduce

1. Clone repo.

2. Run DB (change the port so that .env and docker-compose are synced) using docker compose up -d.

3. Run a production build and start the preview: pnpm build && pnpm start

At this point, it should be working fine.

4. Upgrade next to 13.4, and rerun the above commands: pnpm build && pnpm start.

You should now get a 500 error and something like this TypeError: Cannot read properties of null (reading 'useMemo').

See demo:

CleanShot.2023-05-18.at.12.27.22.mp4

Describe the Bug

When upgrading to 13.4, our websockets example suddenly started to 500, and getting some cannot access property of undefined errors when prepassing on the server.

I am really not sure what this issue boils down to, and I've tried making a more minimal repro without much luck... Not even sure if the issue is in Next, but since it got introduced when upgrading I'm starting out here.

Sorry if this is hard to debug and boil down the root cause of... I wish I could provide a more minimal repro...

Expected Behavior

Server not to 500 - just as it does pre-13.4

Which browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

No response

[juliusmarminge]

UPDATE:

Here's a bit more minimal example: https://github.com/juliusmarminge/custom-server-repro

You can turn off the ssr-prepass by toggling this boolean:

https://github.com/juliusmarminge/custom-server-repro/blob/762c53f786ede992ce67471620cc218f72240a67/src/utils/api.ts#L75

and with it off the server doesn't crash on a 500 in production mode.

So yea, might not next specific but it still only breaks in ^13.4 so it must come from some change you guys made, right?

UPDATE 2:

I've now boiled the issue down to 13.3.5-canary.12 and this PR: #49088. Server still works in 13.3.5-canary.11 without crashing. Explicitely disabling appDir fixes the issue.

[shuding]

Could you try the latest canary? I'm wondering if it's fixed with recent changes.

[juliusmarminge]

Could you try the latest canary? I'm wondering if it's fixed with recent changes.

Yep. Works in 13.4.3. Thanks :)

[github-actions]

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