[BUG] With the release of Next.js 16, turbopack is now the default

[mamuk0]

Describe the bug

Hello everyone, I want to report an issue.

Next.js 16 has now been updated to stable, and a final minor version has been released (16.0.1).

With Next.js v16, the TurboPack builder is now stable and the default, meaning Webpack builds will be completely phased out. The problem is this:

When deploying to Cloudflare via opennextjs-cloudflare, only Webpack is supported.

During deployment, you'll notice that environment variables trigger a WARN, indicating that Turbopack is not supported. Then, when the application is built and you try to access it via Cloudflare Workers, you'll receive an “Internal Server Error (500)” error.

And according to another PR, proxy.ts(.js), formerly middleware.ts, which was renamed with Next.js v16, is no longer supported. This error has already been reported in another PR.

Additionally, something I consider important: when you build with webpack in Next.js v16 (next build --webpack), your application can now run without any errors. (On Cloudflare workers)

Next.js V16 is very new and offers useful features. We now want to serve our production builds or newly created applications directly via v16 with turbopack. Will you be making an update for this?

Thank you for your time, and I wish you all the best.

Steps to reproduce

1. create new application with bun (npm, yarn, pnpm) create cloudflare@latest -- my-next-app --framework=next
2. upgrade to next latest (or as described in (cloudflare docs), make your current project compatible with Cloudflare Workers (you will need to download a few things).
3. preview or deploy to the your application

Expected behavior

If the turbopack builder that comes with v16 is also fully stable and added by opennextjs-cloudflare in the same way, I will be very pleased. Because we want to use our applications with the new features.

@opennextjs/cloudflare version

1.11.0

Wrangler version

4.45.3

next info output

Operating System:
  Platform: linux
  Arch: x64
  Version: #1 SMP PREEMPT_DYNAMIC Thu Jun  5 18:30:46 UTC 2025
  Available memory (MB): 15851
  Available CPU cores: 24
Binaries:
  Node: 24.3.0
  npm: 11.6.1
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 16.0.1 // Latest available version is detected (16.0.1).
  eslint-config-next: N/A
  react: 19.2.0
  react-dom: 19.2.0
  typescript: 5.9.3
Next.js Config:
  output: N/A

Additional context

No response

[jonra1993]

Hi @mamuk0 if you are looking for a temporal solution to deploy Nextjs 16, you can check #962 (comment)

[vicb]

See #972