Turbopack: Bun APIs don't work with next

[brrock]

Link to the code that reproduces this issue

https://github.com/brrock/buntestapis/

To Reproduce

Start the app with bun run --bun dev --turbo pack and use the form the api route should fail to compile even though I'm using bun and have bun types installed

Current vs. Expected behavior

I expect this to just use the bun runtime and compile and work simply work but throws this error Error:

 ✓ Compiled /api/s3write in 377ms
 ⨯ ./app/api/s3write/route.ts:2:1
Module not found: Can't resolve 'bun'
  1 | // app/api/s3write/route.ts
> 2 | import { S3Client } from "bun";
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  3 | import { NextResponse } from 'next/server';
  4 |
  5 | // Initialize S3 client

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: kernel 6.12.9-arch1-1
  Available memory (MB): 15763
  Available CPU cores: 4
Binaries:
  Node: 23.6.0
  npm: 10.9.2
  Yarn: N/A
  pnpm: 9.15.4
Relevant Packages:
  next: 15.1.6 // Latest available version is detected (15.1.6).
  eslint-config-next: 15.1.6
  react: 19.0.0
  react-dom: 19.0.0
  typescript: 5.7.3
Next.js Config:
  output: N/A

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

Runtime

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

next dev (local)

Additional context

No response

[luudv]

It seems there are many bugs with the new version. I had to go back to v15.1.5

[brrock2]

It seems there are many bugs with the new version. I had to go back to v15.1.5

it has always been a problem

[brrock]

It seems there are many bugs with the new version. I had to go back to v15.1.5

@luudv do have example

[LarsKumbier]

I have the same problem with the import { sql } from "bun". I've added @types/bun and am directly running bun --bun run node_modules/.bin/next dev --turbopack:

 ⨯ ./app/query/route.ts:2:1
Module not found: Can't resolve 'bun'
  1 | import pg from "pg";
> 2 | import { sql } from "bun";
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^

(ignore the unnecessary first code line)

Environment:

• Bun: v1.2.1
• NextJS v15.1.6

[LarsKumbier]

Update: the problem seems to be turbopack. Omiting the --turbopack-option in the commandline, I can properly use bun-native APIs like sql in the dev server as well as in a production build.
@samcx Is this still the right place to work on this issue, since turbopack is so tightly coupled with NextJS? Or should I cross-post to turborepo github?

[brrock]

Yes I think turbo pack and web pack need to also build for bun

[brrock]

Update: the problem seems to be turbopack. Omiting the --turbopack-option in the commandline, I can properly use bun-native APIs like sql in the dev server as well as in a production build.
@samcx Is this still the right place to work on this issue, since turbopack is so tightly coupled with NextJS?

Thanks will try

[brrock]

It could be napi-rs (turbo pack builder)producing node code and doesn't know about bun

[brrock]

@samcx this turbopack error

[samcx]

@LarsKumbier This is the right place for Turbopack issues!

[LarsKumbier]

@samcx Thank you - any more information I can provide for the replication of the issue or debugging?

[heymattiarighetti]

Can't get my head around it and make it work...

I was on NextJS 15.1.6 with turbopack on

• Tried without turbopack: ❌
• Downgraded to NextJS 15.1.5: ❌
• Downgraded to 15.1.5 without turbopack: ❌

Module not found: Can't resolve 'bun'
> 1 | import { s3 } from "bun";

[LarsKumbier]

@heymattiarighetti it definetly works for me without turbopack.

• did you install @types/bun?
• did you make sure that you enforce nextjs to run with bun instead of nodejs, and without the default --turbopack option?

$ bun --bun run node_modules/.bin/next dev

Just tested it again (successfully) with Next.JS 15.1.6. If it still doesn't work for you, please start the dev server and post a ps -Af with the relevant processes.

[heymattiarighetti]

@LarsKumbier yes, I later realized it works with turbopack and the latest NextJS...

What doesn't work instead is the built s3 object support, even when running it from bun instead of nodejs

These are my processes:

Handles  NPM(K)    PM(K)      WS(K)     CPU(s)     Id  SI ProcessName                                
-------  ------    -----      -----     ------     --  -- -----------                                
    139       9    79080      41804       0,06  15176   5 bun                                        
     56       4      656       2964       0,00  13612   5 next                                       

but the error persists

Module not found: Can't resolve 'bun'
> 1 | import { s3 } from "bun";

I also tried it on a completely new NextJS project (with the correct @types/bun and everything)

What's weird is that even a simple console.log(Bun.version); returns a [ Server ] Error: Bun is not defined 🤷‍♂

I'm losing my mind on this!

[LarsKumbier]

@heymattiarighetti

A Bun.version will fail, because you cased the module wrong - it's supposed to be "bun", which works for me:

import { version } from "bun";
console.log(version);

But it absolutely does not work with --turbopack, even in the newest version, and even in the newest canary version (15.2.0-canary.41). My guess is that you did the same mistake I did and did not use the import - which will consequently be removed by turbopack, so it looks like its working, but in reality, it does not:

// with turbopack
$ bun --bun run node_modules/.bin/next dev --turbopack
   ▲ Next.js 15.2.0-canary.41 (Turbopack)
   - Local:        http://localhost:3000
   - Network:      http://192.168.178.53:3000
   - Environments: .env
   - Experiments (use with caution):
     · ppr

 ✓ Starting...
 ✓ Ready in 986ms
 ○ Compiling /seed ...
 ✓ Compiled /seed in 687ms
 ⨯ ./app/seed/route.ts:2:1
Module not found: Can't resolve 'bun'
  1 | import bcrypt from "bcrypt";
> 2 | import { sql, TransactionSQL } from "bun";
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[...]

// without turbopack
$ bun --bun run node_modules/.bin/next dev
   ▲ Next.js 15.2.0-canary.41
   - Local:        http://localhost:3000
   - Network:      http://192.168.178.53:3000
   - Environments: .env
   - Experiments (use with caution):
     · ppr

 ✓ Starting...
 ✓ Ready in 1391ms
 ○ Compiling /seed ...
 ✓ Compiled /seed in 1392ms (406 modules)
 GET /seed 200 in 1609ms

AFAIK, you must not use turbopack for the time being.

[brrock]

Yep @samcx this 100% turbo pack anyone willing to work on this and possibly add deno support

[brrock]

@LarsKumbier yes, I later realized it works with turbopack and the latest NextJS...

What doesn't work instead is the built s3 object support, even when running it from bun instead of nodejs

These are my processes:

Handles  NPM(K)    PM(K)      WS(K)     CPU(s)     Id  SI ProcessName                                
-------  ------    -----      -----     ------     --  -- -----------                                
    139       9    79080      41804       0,06  15176   5 bun                                        
     56       4      656       2964       0,00  13612   5 next                                       

but the error persists

Module not found: Can't resolve 'bun'
> 1 | import { s3 } from "bun";

I also tried it on a completely new NextJS project (with the correct @types/bun and everything)

What's weird is that even a simple console.log(Bun.version); returns a [ Server ] Error: Bun is not defined 🤷‍♂

I'm losing my mind on this!

Next will need to import if they spot this

[heymattiarighetti]

@heymattiarighetti

But it absolutely does not work with --turbopack, even in the newest version, and even in the newest canary version (15.2.0-canary.41). My guess is that you did the same mistake I did and did not use the import - which will consequently be removed by turbopack, so it looks like its working, but in reality, it does not:

[...]

AFAIK, you must not use turbopack for the time being.

I'm not sure what changed between my earlier tests and this, but now it works! FINALLY!

This is how it ran:

bun --bun run node_modules/.bin/next dev

More specifically, I have the "dev": "next dev" script in my package, so I did bun --bun run dev

Also, set up the custom script on Vercel and it works fine

(waiting the --turbopack fix now 😁)

Thanks a lot, @LarsKumbier!!