[Turbopack + Next.js] "Next.js package not found" error after monorepo changes, persists even after reverting

[RunyShark]

Description:
I’m facing a strange issue while working with a Turbopack + Next.js monorepo.
Everything was working fine until I made some configuration changes in the monorepo. Right after that, this error started appearing.

Steps I’ve tried so far:

1. Reinstalled dependencies (node_modules) → issue persists.
2. Cloned the repository without the previous changes → issue persists.

Unfortunately, I cannot share a reproducible environment at this time.

Environment:

• Node.js: 23.2.0
• Bun: 1.2.18
• OS: Windows 11 Pro (build 26100)
• CPU: AMD Ryzen 9 7950X3D
• RAM: 128 GB
• GPU: NVIDIA GeForce RTX 5070 Ti — Driver 580.97
• Storage: SSD (931.5 GB and 953.9 GB)

Versions:

• "turbo": "^2.1.3"
• "next": "15.4.3"

Error message:

Next.js package not found

Debug info:

• Execution of get_entrypoints_with_issues_operation failed
• Execution of EntrypointsOperation::new 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 get_next_package failed
• Next.js package not found

Steps before the error:

1. Project was working normally.
2. Made configuration changes in the monorepo (Turbopack + Next.js).
3. Ran the project → error appeared.
4. Reinstalled dependencies → no change.
5. Cloned repo without previous modifications → error persists.

Additional notes:

• The issue occurs even when restoring the project to a previously working state.
• No minimal reproducible repository is available at the moment.

[icyJoseph]

Hi,

This usually happens when there's multiple lock files in the folder structure.

• Turbopack Error: Next.js package not found #78192 (comment)

Depending on your monorepo setup, node_modules can be hoisted, but the presence of a nested lock-file, sort of tells Next.js to look for the dependency on that lower level folder, but the dependency was hoisted by your package manager. It really depends on your setting, but this info ought to help you out.

In later versions, we are adding more warnings with helpful indications as to what's happening, and possible solutions.