Unable to find type [System.Web.HttpUtility] in PowerShell

Question

I'm trying to obtain an access token for a Microsoft Translator application by using PowerShell, but certain commands in the process fail as a result of the error:

Unable to find type [System.Web.HttpUtility]

Before receiving this error, I copied and pasted the code from this MSDN page into the PowerShell ISE, and replaced the placeholder values with my actual credentials:

# ...
$ClientID = '<Your Value Here From Registered Application>'
$client_Secret = ‘<Your Registered Application client_secret>'

# If ClientId or Client_Secret has special characters, UrlEncode before sending request
$clientIDEncoded = [System.Web.HttpUtility]::UrlEncode($ClientID)
$client_SecretEncoded = [System.Web.HttpUtility]::UrlEncode($client_Secret)
# ...

What additional code do I need to add for this to work?

Solution

You need to load the System.Web assembly. Use the Add-Type cmdlet like so,

PS C:\> [System.Web.HttpUtility]::UrlEncode("www.google.com")
Unable to find type [System.Web.HttpUtility].

PS C:\> Add-Type -AssemblyName System.Web
PS C:\> [System.Web.HttpUtility]::UrlEncode("www.google.com")
www.google.com