Experiences installing Claude Code

24d (edited) • Wins

I hit problems installing some base software like npm and claude code - here's what I learned, I hope it helps! BTW I am running this in Windows so if you're running under a different OS it won't work! This is my experience - it might help, but it might not.

If you are on the classroom course orientation section "Start here" and you've been through the lesson steps, at the end is a section called "What to do today". In it is some technical instructions about installing Claude Code and it says to open your terminal and execute this line

npm install -g @anthropic-ai/claude-code

BTW, if you don't know what it means by "terminal", it is referring to the IDE terminal - e.g. Cursor which you should have installed in a previous lesson - screenshot attached

When I did run it I got the following error:

npm : The term 'npm' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.

The course says if npm isn't installed install node.js. This was the case for me (because I received the error above), as instructed I navigated to https://nodejs.org and downloaded the LTS version. When it has installed, close the Cursor program and restart it.

I re-executed the npm install command in my terminal, the error message I had previously got had changed to

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.

What this means is that node.js is installed but the terminal doesn't have permission to run the script (npm.ps1). To confirm this run the following command in the terminal

Get-ExecutionPolicy -List

this will list the execution policies

I got this

Scope ExecutionPolicy

----- ---------------

MachinePolicy Undefined

UserPolicy Undefined

Process Undefined

CurrentUser Undefined

LocalMachine Restricted

You will see the LocalMachine is restricted.

To grant permission I had to run the following steps. There could possibly be other ways to do this but this worked for me

On your Start button, type Powershell - it should find Windows Powershell, right mouse click and click "run as administrator"
This will start a new powershell session that looks like a command line with a cursor blinking after PS C:\WINODWS\system32>
run this command Set-ExecutionPolicy -Scope LocalMachine -ExecutionPolicy Unrestricted
you will prompted to execute the policy change - enter Y
this should have made the change

Go back to cursor and re-run

Get-ExecutionPolicy -List

the LocalMachine scope should now display: Unrestricted

Now you should be all set to install claude code

npm install -g @anthropic-ai/claude-code

oh dear more errors

npm error code UNABLE_TO_VERIFY_LEAF_SIGNATURE

npm error errno UNABLE_TO_VERIFY_LEAF_SIGNATURE

npm error request to https://registry.npmjs.org/@anthropic-ai%2fclaude-code failed, reason: unable to verify the first certificate; if the root CA is installed locally, try running Node.js with --use-system-ca

npm error A complete log of this run can be found in: C:\Users\simon\AppData\Local\npm-cache\_logs\2026-05-29T11_31_37_605Z-debug-0.log

I googled around and found this article

https://stackoverflow.com/questions/20747817/error-unable-to-verify-leaf-signature-phonegap-installation

it suggests to run this command

npm config set strict-ssl false

I did this and then attempted to re-install claude code and it finally worked

IMPORTANT

After you've completed this you MUST run this command

npm config set strict-ssl true

This is because you could leave your machine vulnerable if you don't.

Claude is now installed and good to go!

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