[Turbopack 15.4] Vc<FileSystemPath>("").join("../R:\test\apps\web") leaves the filesystem root #81628
Description
Link to the code that reproduces this issue
https://github.com/PAXANDDOS/nextjs-canary-turbo-reproduction
To Reproduce
If using the provided reproduction repository, skip to number 5.
- Start with the template:
bunx create-turbo@latest --example basic(or npm/pnpm alternative) - Go to
apps/docs/package.jsonandapps/web/package.json, editnextversion to be15.4.1 - Run
bun updateto update to these versions - Add
turbopack.rootconfiguration option to point to the monorepo root - Run
bun dev - Go to localhost:3000 or localhost:3001
- See the error in the terminal
Current vs. Expected behavior
Current behaviour
The webpage shows Internal Server Error and a huge error logged to the terminal:
web:dev: ✓ Ready in 949ms
web:dev: ✓ Compiled /_not-found/page in 3ms
web:dev: ⨯ [Error [TurbopackInternalError]: Failed to write app endpoint /_not-found/page
web:dev:
web:dev: Caused by:
web:dev: - FileSystemPath("").join("../R:\test\apps\web") leaves the filesystem root
web:dev:
web:dev: Debug info:
web:dev: - Execution of TaskId { id: 2147483653 } transient failed
web:dev: - Execution of get_written_endpoint_with_issues_operation failed
web:dev: - Execution of endpoint_write_to_disk failed
web:dev: - Execution of <AppEndpoint as Endpoint>::output failed
web:dev: - Failed to write app endpoint /_not-found/page
web:dev: - Execution of AppEndpoint::output failed
web:dev: - Execution of AppEndpoint::app_page_entry failed
web:dev: - Execution of *get_app_page_entry failed
web:dev: - Execution of AppProject::rsc_module_context failed
web:dev: - Execution of *ModuleAssetContext::new failed
web:dev: - Execution of *AppProject::get_rsc_transitions failed
web:dev: - Execution of AppProject::ecmascript_client_reference_transition failed
web:dev: - Execution of *NextEcmascriptClientReferenceTransition::new failed
web:dev: - Execution of AppProject::client_transition failed
web:dev: ✓ Compiled /_error in 2ms
web:dev: - Execution of *FullContextTransition::new failed
web:dev: - Execution of AppProject::client_module_context failed
web:dev: - Execution of *ModuleAssetContext::new failed
web:dev: - Execution of AppProject::client_module_options_context failed
web:dev: - Execution of *get_client_module_options_context failed
web:dev: - Execution of Project::execution_context failed
web:dev: - Execution of Project::node_root failed
web:dev: - FileSystemPath("").join("../R:\test\apps\web") leaves the filesystem root]
web:dev: [Error [TurbopackInternalError]: Failed to write page endpoint /_app
web:dev:
web:dev: Caused by:
web:dev: - content is not available as task execution failed
web:dev: - content is not available as task execution failed
web:dev: - FileSystemPath("").join("../R:\test\apps\web") leaves the filesystem root
web:dev:
web:dev: Debug info:
web:dev: - Execution of TaskId { id: 2147483654 } transient failed
web:dev: - Execution of get_written_endpoint_with_issues_operation failed
web:dev: - Execution of endpoint_write_to_disk failed
web:dev: - Execution of <PageEndpoint as Endpoint>::output failed
web:dev: - Failed to write page endpoint /_app
web:dev: - Execution of PageEndpoint::output failed
web:dev: - Execution of PageEndpoint::client_chunks failed
web:dev: - Execution of PageEndpoint::client_evaluatable_assets failed
web:dev: - content is not available as task execution failed
web:dev: - Execution of PageEndpoint::client_module failed
web:dev: - content is not available as task execution failed
web:dev: - Execution of *create_page_loader_entry_module failed
web:dev: - Execution of PagesProject::client_module_context failed
web:dev: - Execution of *ModuleAssetContext::new failed
web:dev: - Execution of PagesProject::client_module_options_context failed
web:dev: - Execution of *get_client_module_options_context failed
web:dev: - Execution of Project::execution_context failed
web:dev: - Execution of Project::node_root failed
web:dev: - FileSystemPath("").join("../R:\test\apps\web") leaves the filesystem root]
...
web:dev: ✓ Compiled /favicon.ico in 0msExpected behaviour
Template runs successfully, pages are rendered, terminal has no errors.
Provide environment information
Operating System:
Platform: win32
Arch: x64
Version: Windows 11 Pro
Available memory (MB): 32681
Available CPU cores: 16
Binaries:
Node: 24.4.0
npm: 11.4.2
Yarn: N/A
pnpm: N/A
bun: 1.2.18
Relevant Packages:
next: 15.4.1 // Latest available version is detected (15.4.1).
eslint-config-next: N/A
react: 19.1.0
react-dom: 19.1.0
typescript: 5.8.3
Next.js Config:
output: N/AWhich area(s) are affected? (Select all that apply)
Turbopack
Which stage(s) are affected? (Select all that apply)
next dev (local), next build (local)
Additional context
Originally posted by @terrymun in #80750.
Important notes:
- Became broken after Turbopack: Allow distdir in project directory, outside of the application #80683
- Not specifically Windows related (according to the original discussion)
- Impacts only(?) monorepo repositories like this one from the Tubrorepo template
Affected versions
- Stable:
15.4.0,15.4.1,15.4.2 - Canary:
15.4.0-canary.89through15.4.0-canary.130,15.4.2-canary.0through15.4.2-canary.8 - Latest working version:
15.4.0-canary.88