Next.js project doesn't work with Yarn 4.6.0 using Turbopack

[GlittersIsGold]

Link to the code that reproduces this issue

https://github.com/GlittersIsGold/turboyarnext

To Reproduce

1. install yarn 4.6.0 - npm install -g yarn@latest

2. check yarn version - yarn -v should output 4.6.0

3. init next-app with yarn - yarn create next-app turboyarnext

4. Follow the prompts, simply answer Yes to use Turbopack

✔ Would you like to use TypeScript? … No / Yes - Y
✔ Would you like to use ESLint? … No / Yes - Y
✔ Would you like to use Tailwind CSS? … No / Yes - N
✔ Would you like your code inside a `src/` directory? … No / Yes - N
✔ Would you like to use App Router? (recommended) … No / Yes - Y
✔ Would you like to use Turbopack for `next dev`? … No / Yes - Y
? Would you like to customize the import alias (`@/*` by default)? › No / Yes - N

Creating a new Next.js app in /Users/GlittersIsGold/Documents/Programms/turboyarnext.

Using yarn.

Initializing project with template: app 

Installing dependencies:
- react
- react-dom
- next

Installing devDependencies:
- typescript
- @types/node
- @types/react
- @types/react-dom
- eslint
- eslint-config-next
- @eslint/eslintrc

! The local project doesn't define a 'packageManager' field. Corepack will now add one referencing yarn@1.22.22+sha512.a6b2f7906b721bba3d67d4aff083df04dad64c399707841b7acf00f6b133b7ac24255f2652fa22ae3534329dc6180534e98d17432037ff6fd140556e2bb3137e.
! For more details about this field, consult the documentation at https://nodejs.org/api/packages.html#packagemanager

➤ YN0000: · Yarn 4.6.0
➤ YN0000: ┌ Resolution step
➤ YN0085: │ + @eslint/eslintrc@npm:3.2.0, @types/node@npm:20.17.12, @types/react-dom@npm:19.0.2, and 319 more.
➤ YN0000: └ Completed in 3s 599ms
➤ YN0000: ┌ Fetch step
➤ YN0000: └ Completed
➤ YN0000: ┌ Link step
➤ YN0000: │ ESM support for PnP uses the experimental loader API and is therefore experimental
➤ YN0007: │ sharp@npm:0.33.5 must be built because it never has been before or the last one failed
➤ YN0000: └ Completed in 1s 361ms
➤ YN0000: · Done with warnings in 5s 185ms
Initialized a git repository.

Success! Created turboyarnext at /Users/GlittersIsGold/Documents/Programm/turboyarnext

5. proceed to project dir, install deps and try to start app

cd turboyarnext && yarn && yarn dev

➜  turboyarnext git:(main) yarn
➤ YN0000: · Yarn 4.6.0
➤ YN0000: ┌ Resolution step
➤ YN0000: └ Completed
➤ YN0000: ┌ Fetch step
➤ YN0000: └ Completed
➤ YN0000: ┌ Link step
➤ YN0000: │ ESM support for PnP uses the experimental loader API and is therefore experimental
➤ YN0000: └ Completed
➤ YN0000: · Done with warnings in 0s 272ms

➜  turboyarnext git:(main) yarn dev
   ▲ Next.js 15.1.4 (Turbopack)
   - Local:        http://localhost:3000
   - Network:      http://79.164.27.29:3000

 ✓ Starting...
FATAL: An unexpected Turbopack error occurred. Please report the content of /var/folders/st/_ln0wwtj7xl3pd3l2sv8xh700000gn/T/next-panic-fc976d666c1f252cd743c4aa6d34fee8.log, along with a description of what you were doing when the error occurred, to https://github.com/vercel/next.js/issues/new
[Error [TurbopackInternalError]: Next.js package not found

Debug info:
- Execution of get_entrypoints_with_issues failed
- Execution of Project::entrypoints failed
- Execution of AppProject::routes failed
- Execution of directory_tree_to_entrypoints_internal failed
- Execution of directory_tree_to_loader_tree failed
- Execution of *FileSystemPath::join failed
- Execution of get_next_package failed
- Next.js package not found]

6. Get an error

cat /var/folders/st/_ln0wwtj7xl3pd3l2sv8xh700000gn/T/next-panic-fc976d666c1f252cd743c4aa6d34fee8.log
---------------------------
Next.js package not found

Debug info:
- Execution of get_entrypoints_with_issues failed
- Execution of Project::entrypoints failed
- Execution of AppProject::routes failed
- Execution of directory_tree_to_entrypoints_internal failed
- Execution of directory_tree_to_loader_tree failed
- Execution of *FileSystemPath::join failed
- Execution of get_next_package failed
- Next.js package not found

Current vs. Expected behavior

Expected to launch Next app via Turbopack & yarn dev, observed to Fatal Turbopack error, package not found.

Next package already exists in package.json

{
  "name": "turboyarnext",
  "version": "0.1.0",
  "private": true,
  "scripts": {
    "dev": "next dev --turbopack",
    "build": "next build",
    "start": "next start",
    "lint": "next lint"
  },
  "dependencies": {
    "next": "15.1.4",
    "react": "^19.0.0",
    "react-dom": "^19.0.0"
  },
  "devDependencies": {
    "@eslint/eslintrc": "^3",
    "@types/node": "^20",
    "@types/react": "^19",
    "@types/react-dom": "^19",
    "eslint": "^9",
    "eslint-config-next": "15.1.4",
    "typescript": "^5"
  },
  "packageManager": "yarn@1.22.22+sha512.a6b2f7906b721bba3d67d4aff083df04dad64c399707841b7acf00f6b133b7ac24255f2652fa22ae3534329dc6180534e98d17432037ff6fd140556e2bb3137e"
}

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.2.0: Fri Dec  6 19:02:41 PST 2024; root:xnu-11215.61.5~2/RELEASE_ARM64_T6030
  Available memory (MB): 18432
  Available CPU cores: 12
Binaries:
  Node: 20.14.0
  npm: 10.7.0
  Yarn: 4.6.0
  pnpm: N/A
Relevant Packages:
  next: 15.1.4
  eslint-config-next: 15.1.4
  react: 19.0.0
  react-dom: 19.0.0
  typescript: 5.7.2
Next.js Config:
  output: N/A

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

create-next-app

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

next dev (local)

Additional context

No response

[didix16]

Yeah, here having the same issue!

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[hamidrezahanafi]

Will it work if you manually change in package.json that is generated "packageManager": "yarn@1.22.22+sha512.a6b2f7906b721bba3d67d4aff083df04dad64c399707841b7acf00f6b133b7ac24255f2652fa22ae3534329dc6180534e98d17432037ff6fd140556e2bb3137e" to "packageManager": "yarn@4.6"?

[GlittersIsGold]

Will it work if you manually change in package.json "packageManager": "yarn@4.6"?

already tried, still not working.

if you change this line to "yarn@4.6" , you will get an error:

String does not match the pattern of "(npm|pnpm|yarn|bun)@\d+\.\d+\.\d+(-.+)?".

Inserting this line "packageManager": "yarn@4.6.0" doesn't make sense, FATAL Turbopack error occurs:

FATAL: An unexpected Turbopack error occurred. Please report the content of /var/folders/st/_ln0wwtj7xl3pd3l2sv8xh700000gn/T/next-panic-1a8855b3640d2770e0b8a87ecdf5640.log, along with a description of what you were doing when the error occurred, to https://github.com/vercel/next.js/issues/new
[Error [TurbopackInternalError]: Next.js package not found

Debug info:
- Execution of get_entrypoints_with_issues failed
- Execution of Project::entrypoints failed
- Execution of AppProject::routes failed
- Execution of directory_tree_to_entrypoints_internal failed
- Execution of directory_tree_to_loader_tree failed
- Execution of *FileSystemPath::join failed
- Execution of get_next_package failed
- Next.js package not found]

I've seen the same issue in berry repo, still no decisions - yarnpkg/berry#6642

There's also no info in documentation

[akdombrowski]

FYI. I've got the same problem. Running yarn next dev does work in the same project without any other changes. So, it definitely seems to indicate Turbopack as the culprit.
I also tried reverting to yarn@4.5.3 (yarn set version 4.5) and yarn@4.4.1. They both gave the same errors as 4.6.0.

[ParwarYasinQadr]

i encounter same issue by changing to npm I solved the problem but also one of my friend tried with yarn 1.22 it worked fine

[lcs07]

I'm getting the same error with yarn 4.6.0. If I remove --turbopack from next dev --turbopack and run it, it works fine.

[ParwarYasinQadr]

the turbo pack is really a good thing to have it just boost everything in development server to another level