Invoke-Command with remote session: Cannot validate argument on parameter

Question

I wrote a script to restart a few ASP.NET websites on a remote server:

$computerName = #...
$password = #...
$secureStringPassword = ConvertTo-SecureString -AsPlainText -Force -String $password
$userName = #...
$credential= New-Object System.Management.Automation.PSCredential ($userName, $secureStringPassword)
$websiteNames = #..., #..., #...

Get-PSSession -ComputerName $computerName -Credential $credential | Remove-PSSession 

$psSession = New-PSSession -ComputerName $computerName -Credential $credential

Invoke-Command -Session $psSession -ScriptBlock { $websiteNames | foreach{ Stop-Website -Name $_ } }
Invoke-Command -Session $psSession -ScriptBlock { $websiteNames | foreach{ Start-Website -Name $_ } }

$psSession | Remove-PSSession

For some reasons my Invoke-Command do not run properly, I have the following error message:

Cannot validate argument on parameter 'Name'. The argument is null. Provide a valid value for the argument, and then try running the command again.

When the commands are run after an Enter-PSSession it works fine within a -ScriptBlock it kinda mess up the -Name parameter, any idea how to fix that up?

Mike L'Angelo Mike L'Angelo · Accepted Answer · 2019-05-02T12:04:15

The remote session cannot access the variables you have defined locally. They can be referenced with $using:variable

Invoke-Command -Session $psSession -ScriptBlock { $using:websiteNames | foreach{ Stop-Website -Name $_ } }
Invoke-Command -Session $psSession -ScriptBlock { $using:websiteNames | foreach{ Start-Website -Name $_ } }

More information in the about_remote_variables help:

get-help about_remote_variables -Full

Invoke-Command with remote session: Cannot validate argument on parameter

2 Answers