After updates cannot run WPF code: Unable to find type [Windows.Markup.XamlReader]

From @music2myear on June 15, 2017 17:38

• VSCode Version: 1.13.1
• OS Version: Win10 1703 (OS Build 15063.413
• PowerShell Extension Version: 1.3.2

Steps to Reproduce:

WPF code not working.

Code:

[xml]$xaml = @"
<Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    x:Name="Window" Title="Initial Window" WindowStartupLocation = "CenterScreen" 
    Width = "800" Height = "600" ShowInTaskbar = "True">
</Window>
"@ 

$reader=(New-Object System.Xml.XmlNodeReader $xaml)
$Window=[Windows.Markup.XamlReader]::Load( $reader )

Output:

Unable to find type [Windows.Markup.XamlReader]. At C:\path\script.ps1:12 char:9

• $Window=[Windows.Markup.XamlReader]::Load( $reader )

•     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
  

  • CategoryInfo : InvalidOperation: (Windows.Markup.XamlReader:TypeName) [], RuntimeException
  • FullyQualifiedErrorId : TypeNotFound

Running same code in PowerShell ISE works just fine.

Before issue began, three different installs occurred on my computer:

• VS Code updated from 1.13.0 to 1.13.1
• OS installed updates KB4022725 and KB4022405
• ATI Video Driver update included .NET 4.5 runtime

I have confirmed that .NET 4.7 is still loaded in system. PowerShell ISE runs same code just fine (simple window is displayed).

Copied from original issue: Microsoft/vscode#28827

[music2myear]

@daviwil Yes, prior to the updates noted in the OP I was able to run WPF code without issue. These and other tutorial scripts worked just fine pasting the code into a ps1 file in VS Code, saving, and executing in either the Powershell.exe or “PowerShell Integrated” terminals. Both worked the same and both ran WPF code.

Earlier today I thought there might have been an issue with PS on my computer and so just completed the standard Win10 corruption repair process including sfc /scannow, the full DISM health check, and a repair install when there were issues the other items were unable to resolve (checking the CBS logs showed these were not PowerShell-related, but apparently back checksums on .lnk files relevant to the RSAT tools).

Checking post-repair install I’m having the same issue.

All that out of the way, adding the Add-Type line you referenced appears to have done the trick.

I know this wasn’t being reference in my PS profiles, so I’m not sure how it was working before without this line being in the scripts somewhere, but they were.

As these scripts are intended for use somewhere besides my own computer, it makes sense for this line to be in the code, so perhaps having this problem now and you getting me the solution means it won’t be a surprise failure later.

I appreciate the information. We can consider this issue resolved.

[daviwil]

Double the support, double the fun 😉