New Post: Specified cast is not valid. (at

Found the issue, underneath these keys was a DWORD value with invalid data. Once I deleted that value it worked as expected. For the OP, I was able to find what keys were having the problem using this script:

$regKeyApplications = @( "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall", "HKLM:\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall" )
Foreach ($regKey in $regKeyApplications ) {
    If (Test-Path $regKey -ErrorAction SilentlyContinue) {
        $regKeyApplication = Get-ChildItem $regKey -ErrorAction SilentlyContinue | ForEach-Object { 
            Write-Host $_.PsPath
            Get-ItemProperty -LiteralPath $_.PsPath 
            }
    }
}

This script is essentially just the lines of code from "AppDeployToolkitMain.ps1" that were having the original error. I changed it very slightly to output the PSPath to console before Get-ItemProperty was called so that I could match up the errors to the registry key that was having the problem. Hopefully this can help the OP.

Thanks for the great toolkit!