powershell input string not in correct format - powershell

Question

I am having a bit of an annoying problem that I just can't seem to find the answer to. I am using a powershell script to uninstall programs and a batch file to run the script on the programs I want removed in a particular order. I found the script on the web and it works perfectly on my test machine. The problem begins when I run the script on another machine.
This is the error I get:
Error formatting a string: Input string was not in a correct format..
At C:\Users\currentuser\Desktop\uninstallScript.ps1:60 char:1
+ &msiexec `/qn `/x `{$stringer`}
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: ({{0}}}:String) [],
RuntimeException
+ FullyQualifiedErrorId : FormatError
And here is the PowerShell script:
###########################################
######## Written by DC 2012-02-13#########
###########################################
<#
.SYNOPSIS
Uninstalls software by only passing the Software Title.
Should work with all msiexec string uninstallers.
For uninstall commands that end in uninstall.exe or helper.exe a "/S" is
used as a switch.
.PARAMETER DisplayName
The complete or partial name of the software being uninstalled. Must appear
as shown in add / remove programs (case insenstive).
.EXAMPLE
Uninstall-Program Java
Will search the registry and uninstall all instances of Java from a machine.
#>
[cmdletBinding()]
Param
(
[String]$DisplayName = $(throw "DisplayName is Required")
)
Set-Variable -Name ThirtyMachine -Value
"HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall" -Option Constant
Set-Variable -Name SixtyMachine -Value
"HKLM:\SOFTWARE\WOW6432NODE\Microsoft\Windows\CurrentVersion\Uninstall" -
Option Constant
Set-Variable -Name ThirtyUser -Value
"HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall" -Option Constant
Set-Variable -Name SixtyUser -Value
"HKCU:\SOFTWARE\WOW6432NODE\Microsoft\Windows\CurrentVersion\Uninstall" -
Option Constant
$regs = $ThirtyMachine,$SixtyMachine,$ThirtyUser,$SixtyUser
foreach ($reg in $regs)
{
if(Test-Path $reg)
{
$SubKeys = Get-ItemProperty "$reg\*"
}
else
{
$SubKeys = $null
}
foreach($key in $SubKeys)
{
if($key.DisplayName -match "$DisplayName")
{
Write-Host "Found Software " $key.DisplayName
if($key.UninstallString -match "^msiexec")
{
$startGUID = $key.UninstallString.IndexOf("{") + 1
$endGuid = $key.UninstallString.IndexOf("}") - $startGUID
$stringer = $key.UninstallString.Substring($startGUID,$endGuid)
Write-Host "Uninstaller Known, now uninstalling"
&msiexec `/qn `/x `{$stringer`}
}
if($key.UninstallString.Replace('"',"") -match 'uninstall.exe\Z' -or
$key.UninstallString.replace('"',"") -match 'helper.exe\Z' )
{
$stringer = $key.UninstallString.Replace('"',"")
if(Test-Path $stringer )
{
Write-Host "Possible Uninstaller found. Trying" $key.UninstallString "/S"
&$stringer /S
}
}
}
}
}
I debugged the code in PowerShell ISE to verify that the variable $stringer contained the correct value. So I believe this has something to do with the version of powershell being run on the 2 machines. The test machine, where the script works, is version 2 whereas the other machine, where I get the error, is version 4. I've barely begun to learn powershell so I am scratching my head at this one. Hopefully it is simple to resolve. I appreciate any help offered.

Answer 1

The escape characters ``` in your msiexec call are causing the error and shouldn't be there. Here's a way to call it how you are properly:
& msiexec /qn "/x{$stringer}"
Alternatively, you can utilize Start-Process and wait on the process:
Start-Process -FilePath 'msiexec' -ArgumentList #('/qn','/x',"{$stringer}") -Wait