Description
Type: Bug
VS Code fails to open valid UNC file paths in Markdown documents, even with the appropriate settings configured. The same UNC file can be opened by other tools (e.g., notepad.exe, Python), and the Markdown link is recognized visually in the preview — but clicking the link results in an error.
🔁 Reproduction Steps
Create a .md file with a UNC link:
With this Syntax, the Preview show a link.
But VS Code can't find: "2025-10-08 17:52:19.121 [error] [Window] Error: The editor could not be opened because the file was not found."
Confirm file is accessible: ✅ notepad.exe "\ts453\wissen\Resources\readme.md" → works ✅ Python open() with UNC → works
❌ code "\ts453\wissen\Resources\readme.md" → fails
Try clicking the link in Markdown Preview (Ctrl+Click): File is not opened
Console log shows:
Error: Unable to read file '\ts453\wissen\Resources\readme.md' (Unknown (FileSystemError): UNC host 'ts453' access is not allowed. Please update the 'security.allowedUNCHosts' setting if you want to allow this host.) 🔧 Configuration
Relevant settings.json entries:
"security.allowedUNCHosts": ["ts453"], "markdown.unsafe.allowUNC": true, "security.workspace.trust.untrustedFiles": "open"
📚 RFC / Standards Notes
- file:// is defined in RFC 8089
- UNC syntax (\host\share) is fully supported by Windows
- Markdown itself (e.g., CommonMark) does not forbid such links
- File can be accessed programmatically and by Windows natively
❗Expected Behavior
When the Markdown preview recognizes a file:// link pointing to a UNC path, VS Code should resolve and open the file, especially if the path has been explicitly allowed via security.allowedUNCHosts.
✅ Workaround
Using notepad or Python to access the file confirms that the issue is within VS Code’s internal file resolution logic, not a system or network-level restriction.
🔧 Configuration
Relevant settings.json entries:
"security.allowedUNCHosts": ["ts453"], "markdown.unsafe.allowUNC": true, "security.workspace.trust.untrustedFiles": "open"
📚 RFC / Standards Notes
file:// is defined in RFC 8089
UNC syntax (\host\share) is fully supported by Windows
Markdown itself (e.g., CommonMark) does not forbid such links. File can be accessed programmatically and by Windows natively
💬 Final Notes
This appears to be a bug or unintended policy handling in Markdown preview or file system access logic. If intentional, it should be clearly documented. If not, it would help many Windows-based users working with network shares via Markdown.
VS Code version: Code 1.104.3 (385651c938df8a906869babee516bffd0ddb9829, 2025-10-02T12:30:51.747Z) OS version: Windows_NT x64 10.0.26100 Modes:
| Item | Value |
|---|---|
| CPUs | AMD Ryzen 7 5700U with Radeon Graphics (16 x 1797) |
| GPU Status | 2d_canvas: enableddirect_rendering_display_compositor: disabled_off_okgpu_compositing: enabledmultiple_raster_threads: enabled_onopengl: enabled_onrasterization: enabledraw_draw: disabled_off_okskia_graphite: disabled_offtrees_in_viz: disabled_offvideo_decode: enabledvideo_encode: enabledvulkan: disabled_offwebgl: enabledwebgl2: enabledwebgpu: enabledwebnn: disabled_off |
| Load (avg) | undefined |
| Memory (System) | 31.34GB (12.64GB free) |
| Process Argv | Z:\ --goto Z:\status.md |
| Screen Reader | no |
| VM | 0% |
| Extension | Author (truncated) | Version |
|---|---|---|
| emojisense | bie | 0.10.0 |
| markdown-preview-github-styles | bie | 2.2.0 |
| gitlens | eam | 17.6.0 |
| black-formatter | ms- | 2025.2.0 |
| debugpy | ms- | 2025.10.0 |
| isort | ms- | 2025.0.0 |
| pylint | ms- | 2025.2.0 |
| python | ms- | 2025.14.0 |
| vscode-pylance | ms- | 2025.8.3 |
| powershell | ms- | 2025.2.0 |
| vsliveshare | ms- | 1.0.5959 |
| autodocstring | njp | 0.6.1 |
| material-icon-theme | PKi | 5.27.0 |
| LiveServer | rit | 5.7.9 |
| markdowntable | Tak | 0.13.0 |
| markdown-all-in-one | yzh | 3.6.3 |