PowerShell 给出错误“对象引用未设置到实例对象”

Question

Am receiving an error from my powershell script everytime it runs. However, it does run successfully. I would like to know what is causing the error message. Thanks!

PowerShell:

 [xml]$file = get-content "c:\Windows\personalsettings\PersonalSettings.xml"
  $xmlProperties = $file.SelectNodes("/Objects/Object/Property")
   If ($xmlProperties.Where({ $_.InnerText -eq 'FireFox' }, 'First'))
    {
    Invoke-expression "C:\Windows\SetDefaultBrowser\setdefaultbrowser"
  }
   If ($xmlProperties.Where({ $_.InnerText -eq 'Chrome' }, 'First'))
  { 
  Invoke-expression "C:\Windows\psu\protected\SetDefaultBrowser\setdefaultbrowser"
 }

XML File:

<?xml version="1.0"?>
<Objects>
<Object>
<Property Name="Browser">Firefox</Property>
<Property Name="PDF">Adobe Reader</Property>
</Object>
</Objects>

Answer 1

The xml file is declared with a namespace <?xml version="1.0"?> and that's why it is not selecting the nodes. It will be better to get the values like ordinary objects:

$file = [xml](Get-Content "c:\Windows\personalsettings\PersonalSettings.xml")
$file.objects.object.property | ForEach {
  If ($_.Innertext -eq "Firefox") {
    Invoke-expression "C:\Windows\SetDefaultBrowser\setdefaultbrowser"
  }
  If ($_.Innertext -eq "Chrome") {
    Invoke-expression "C:\Windows\psu\protected\SetDefaultBrowser\setdefaultbrowser"
  }
}