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When the install command your AI gave you stops with "running scripts is disabled on this system"

If you typed npm install or claude the way your AI told you and got red text saying "running scripts is disabled on this system", this post is for you.

Quick answer

Paste the line below into PowerShell, answer Y if it asks, then open a new window. No administrator rights needed.

powershell
Set-ExecutionPolicy -Scope CurrentUser -ExecutionPolicy RemoteSigned

Why it happens

The PowerShell that ships with Windows starts out set to "run no script files at all". Tools like npm install their commands as .ps1 script files, so they are blocked the moment you type them.

Stop it next time

Put this line in first thing on a new PC. Scripts downloaded from the internet stay blocked under this setting, so the safety net is still there.

Take this with you

Red error text does not always mean something is broken. Read what was blocked first (here, a .ps1 file); often it is a one-line setting.

For
Anyone installing AI tools (Claude Code, Codex, npm, Python) on Windows for the first time
Reading time
3 min
Level
Beginner

Yuhoby yuhobuilds

Symptom

I pasted an install command from my AI into PowerShell and got this:

text
npm : File C:\Program Files\nodejs\npm.ps1 cannot be loaded because running scripts is disabled on this system.
For more information, see about_Execution_Policies at https:/go.microsoft.com/fwlink/?LinkID=135170.
    + CategoryInfo          : SecurityError: (:) [], PSSecurityException
    + FullyQualifiedErrorId : UnauthorizedAccess

Instead of npm it may say claude, codex or yarn, or it may happen when you activate a Python virtual environment with .\venv\Scripts\Activate. On Korean Windows the same message reads 「이 시스템에서 스크립트를 실행할 수 없으므로」.

I hit it the day I moved to a new laptop. A posting tool that ran fine on the old laptop stopped with this error. I had changed the setting on the old one at some point and forgotten the setting even existed.

Cause and principle

PowerShell has a safety rule called the execution policy. It decides whether script files (.ps1) may run. Commands you type one at a time always work; only script files are subject to the rule.

The "Windows PowerShell" that comes with every Windows PC starts out with nothing set, which means Restricted: no script files at all.

PolicyMeaning
RestrictedRuns no script files. The default on Windows PCs
RemoteSignedRuns scripts made on your PC. Scripts downloaded from the internet need a signature
UnrestrictedRuns anything. Not recommended

The catch is that npm installs each command as three files. My Node.js folder holds npm, npm.cmd and npm.ps1 side by side. When you type npm in PowerShell, PowerShell picks the .ps1 first, and that file hits the execution policy. Tools installed with npm install -g, such as codex and gemini, get a .ps1 in %APPDATA%\npm the same way.

Side by side on my PC (2026-10-18):

text
Windows PowerShell 5.1 · Restricted   →  npm --version     blocked
Windows PowerShell 5.1 · Restricted   →  npm.cmd --version 12.2.0
PowerShell 7 · RemoteSigned          →  npm --version     12.2.0

PowerShell 7, which I installed separately, was already RemoteSigned on my PC. The built-in blue Windows PowerShell and PowerShell 7 keep separate settings.

Fix

On a PC you keep using, set RemoteSigned for your own account only. No administrator rights needed.

powershell
Set-ExecutionPolicy -Scope CurrentUser -ExecutionPolicy RemoteSigned

If it asks "Do you want to change the execution policy?", answer Y, then close PowerShell and open a new window.

If you would rather not keep the setting, loosen it for the current window only. Closing the window puts it back.

powershell
Set-ExecutionPolicy -Scope Process -ExecutionPolicy RemoteSigned

To avoid the setting entirely, call the .cmd file directly.

powershell
npm.cmd install

Check again

powershell
Get-ExecutionPolicy -List
npm --version

If CurrentUser shows RemoteSigned and npm --version prints a number, you are done.

Pitfalls

  • Do not open everything up with Unrestricted or Bypass. Scripts from the internet would then run without asking.
  • A .ps1 downloaded from the internet is still blocked under RemoteSigned. Read it first, then unblock it with Unblock-File .\file-name.ps1.
  • On a work PC an administrator may have locked this with group policy (MachinePolicy, UserPolicy). The command above will not override that; ask your IT team.
  • The same error appears when another program runs powershell.exe -File script.ps1 internally. I added -ExecutionPolicy Bypass to the line that program uses, so that one script runs and the PC setting stays as it is.

Windows 11Windows PowerShellNode.js (npm)한국어판 Suggest an edit