powershell signing certificate unknownerror

Question

I am following the instructions to sign a script

and I've got to the part where I sign the add-signature.ps1 file so that I can sign my script using it

$cert = @(Get-ChildItem cert:\CurrentUser\My -codesigning)[0]
Set-AuthenticodeSignature add-signature.ps1 $cert

and I get this error:

I've Googled endlessly but found no solutions! I'm running PS in Administrator mode and I've set the policy for CurrentUser to AllSigned

Can anyone help me? Do I need to set all the policies to AllSigned?

UPDATE: Deleting all the Certs and starting again, following the Microsoft instructions: and of course I get an error when I try to run the add-signature.ps1 script - help!

Answer 1

Importing the cert to \CurrentUser\Root as well as TrustedPublisher worked

Answer 2

I came across this question after following the same instructions for signing a Powershell script mentioned by @MarcusR1. And I as well was running into the same issue with the UnknownError when signing my Powershell script.

I eventually found a working solution in Powershell's Github repository. Following the original instructions from Microsoft's instructions I was able to successfully sign my Powershell script by running the following commands:

Export-Certificate -FilePath exported_cert.cer -Cert $cert
Import-Certificate -FilePath exported_cert.cer -CertStoreLocation Cert:\CurrentUser\Root

Set-AuthenticodeSignature -Certificate $cert -FilePath HelloWorld.exe