Deleting a File Named NUL on Windows

Sometimes, due to a bug, files with reserved names like NUL, CON, PRN, AUX, COM1–COM9, or LPT1–LPT9 may appear and cannot be deleted normally.

These names are reserved by Windows for devices, so normal delete operations fail. It is usually caused by a software bug, archive extraction, or script error — not a virus.

Root Cause in CrawlLama

The nul file can be created by Windows batch scripts that use lowercase >nul for output redirection. Under certain conditions (crashes, wrong working directory, Unicode path issues), Windows may create a file named nul instead of redirecting to the NUL device.

Prevention (v1.4.6+)

All batch scripts now include:

1. Uppercase redirection: Changed >nul to >NUL (more reliable on Windows)
2. Auto-cleanup: Each batch script removes any existing nul file on startup
3. Manual cleanup: Run cleanup_nul.bat if the file appears

The fix was applied to:

• setup.bat (lines 5, 10, 108)
• run.bat (line 6)
• run_api.bat (line 6)
• health-dashboard.bat (line 6)

Steps to Delete

1. Using the UNC Path

Open Command Prompt as Administrator:

del "\\?\C:\Path\To\Folder\NUL"

2. Rename then Delete

ren "\\?\C:\Path\To\Folder\NUL" temp.txt
del "\\?\C:\Path\To\Folder\temp.txt"

3. Using Linux/WSL

rm /mnt/c/Path/To/Folder/NUL

Tip: Always use the full path with \\?\ to handle reserved filenames.