Unable to install yarn on windows 10

Question

I installed node v16.13.0, npm v8.1.0 java version 1.8.0_211 and I thought I also have installed yarn, but trying to install expo using yarn global add expo-cli I get:

yarn : File C:\Program Files\nodejs\yarn.ps1 cannot be loaded. The file C:\Program Files\nodejs\yarn.ps1 is not
digitally signed. You cannot run this script on the current system. For more information about running scripts and
setting execution policy, see about_Execution_Policies at https:/go.microsoft.com/fwlink/?LinkID=135170.
At line:1 char:1
+ yarn global add expo-cli
+ ~~~~
    + CategoryInfo          : SecurityError: (:) [], PSSecurityException
    + FullyQualifiedErrorId : UnauthorizedAccess

Then I tried to install yarn again, but now I am 100% unable to get it:

PS C:\Users\user> npm install -g yarn

changed 1 package, and audited 2 packages in 1s

found 0 vulnerabilities

but running yarn --version I get the same error as before:

yarn : File C:\Program Files\nodejs\yarn.ps1 cannot be loaded. The file C:\Program Files\nodejs\yarn.ps1 is not
digitally signed. You cannot run this script on the current system. For more information about running scripts and
setting execution policy, see about_Execution_Policies at https:/go.microsoft.com/fwlink/?LinkID=135170.
At line:1 char:1
+ yarn --version
+ ~~~~
    + CategoryInfo          : SecurityError: (:) [], PSSecurityException
    + FullyQualifiedErrorId : UnauthorizedAccess

Jeremiah

Are you running it on powershell? try running it on command prompt – Ado

By cmd it showed the version that is installed (C:\Users\spike>yarn --version 1.22.15), why can't I get it from powershell? But even using cmd or whatever else, I was unable of using yarn, it was my system environment that had to be changed in the path – Jeremiah

Answer 1

Execute:

Set-ExecutionPolicy -Scope CurrentUser -ExecutionPolicy Unrestricted

Fulmar

Wouldn't recommend this approach as the answer by Saber works (and is safer). – Favorable

Answer 2

I suggest not changing your system policy.

Instead, follow this:

Remove yarn.ps1 from the directory C:\Users%username%\AppData\Roaming\npm\ then try clearing the npm cache at C:\Users%username%\AppData\Roaming\npm-cache\

Surfboard

I have no npm-cache folder – Homesteader

I feel like this is the correct answer. Changing security policies for a single issue is a scary thing, and following these steps corrected the issue for me. – Nosey

In my case the file to remove was C:\Program Files\nodejs\yarn.ps1. After removing it (i renamed it), yarn command works. – Portsalut

I had nvm so it was in C:\Users\%username%\AppData\Roaming\nvm\v16.20.2\ – Bald

Why did windows create those ps1 files? I just deleted all of mine. Mine was found at C:\Program Files\nodejs\yarn.ps1 – Bogie

Answer 3

Under your npm install directory, rename yarn.ps1 to yarn_disabled.ps1. Now whenever you call yarn, the system will fallback to yarn.CMD which does not have the concept of digital signatures unlike PowerShell.

This is recommended over changing execution policy.

Ethiopia