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The mysterious NUL file problem

AI tools sometimes create nul files that you can’t delete normally. Here’s how to fix it.

The problem

Some AI tools (Cursor, Copilot, and similar) accidentally create files named nul, which is a reserved name in Windows. That makes them impossible to delete with File Explorer or a normal del.

You’ll see errors — and the file stays put.

Git won’t push it

Git treats nul as reserved and effectively ignores it, so your remote is usually safe. It can still clutter the working tree and confuse git status.

The solution

Run PowerShell as Administrator and delete via the Windows UNC path:

powershell
cmd /c del /f /q "\\?\C:\YOUR-FOLDER\nul"

Step by step

  1. Open PowerShell as Administrator (right-click Start → Terminal/PowerShell (Admin))
  2. Replace YOUR-FOLDER with the real path
  3. Run the command

Example

powershell
# If your project is in C:\Users\you\projects\my-app
cmd /c del /f /q "\\?\C:\Users\you\projects\my-app\nul"

Why this works

The \\?\ prefix tells Windows to bypass normal path parsing and access the file directly. That lets you target reserved names that normal APIs block.

Other reserved names

Same class of problem:

CON · PRN · AUX · NUL · COM0COM9 · LPT0LPT9

Further reading