How to uninstall MSIs using the Uninstall Path

Note:

• This answer addresses the question as asked.
• js2010's helpful answer shows a much more convenient alternative that avoids the original problem, via the PackageManagement module's Get-Package and Uninstall-Package cmdlets. Note, however, that these cmdlets only support installed applications, and only in the Windows PowerShell edition - by contrast, PowerShell (Core) as of v7.1 lacks the relevant package providers altogether,^[1] and it's unclear (to me) whether they will ever be added.

Problem:

• The uninstallation command lines stored in the UninstallString / QuietUninstallString registry values^[2] are designed for no-shell / from-cmd.exe invocations.

• They therefore can fail from PowerShell if you pass them to Invoke-Expression, namely if they contain unquoted characters that have no special meaning outside shells / to cmd.exe, but are metacharacters in PowerShell, which applies to { and } in your case.

Solutions:

You have two options:

• (a) Simply pass the uninstallation string as-is to cmd /c

  • Note that - unlike when you call msiexec.exe directly from PowerShell or directly from cmd.exe - calling via cmd /c results in synchronous execution of msiexec, which is desirable.

• (b) Split the uninstallation string into executable and argument list, which allows you to call the command via Start-Process, which can give you more control over the invocation.

  • Be sure to use the -Wait switch to ensure that the installation completes before your script continues.

Note: The following commands assume that the uninstall string is contained in variable $UninstallString (the equivalent of $UninstallPath.UninstallString in your code):

Implementation of (a):

# Simply pass the uninstallation string (command line) to cmd.exe
# via `cmd /c`. 
# Execution is synchronous (blocks until the command finishes).
cmd /c $UninstallString

$exitCode = $LASTEXITCODE

The automatic $LASTEXITCODE variable can then be queried for the command line's exit code.

Implementation of (b):

# Split the command line into executable and argument list.
# Account for the fact that the executable name may be double-quoted.
if ($UninstallString[0] -eq '"') {
    $unused, $exe, $argList = $UninstallString -split '"', 3
}
else {
    $exe, $argList = $UninstallString -split ' ', 2
}

# Use Start-Process with -Wait to wait for the command to finish.
# -PassThru returns an object representing the process launched,
# whose .ExitCode property can then be queried.
$ps = if ($argList) {
        Start-Process -Wait -PassThru $exe $argList
      } else {
        Start-Process -Wait -PassThru $exe 
      }
$exitCode = $ps.ExitCode

You could also add -NoNewWindow to prevent console program-based uninstallation command lines from running in a new console window, but note that the only way to capture their stdout / stderr output via Start-Process is to redirect them to files, using the -RedirectStandardOutput / -RedirectStandardError parameters.

Edition-specific / future improvements:

The Start-Process-based method is cumbersome for two reasons:

• You cannot pass whole command lines and must instead specify the executable and arguments separately.

  • GitHub proposal #14347 aims to add support for passing whole command lines.

• In Windows PowerShell (whose latest and final version is 5.1) you cannot pass an empty string or array to the (positionally implied) -ArgumentList parameter (hence the need for two separate calls above).

  • This problem has been fixed in the cross-platform, install-on-demand PowerShell (Core) edition (versions 6 and above).

^{[1] If you don't mind the extra overhead, you can (temporarily) import the Windows PowerShell PackageManagement module even from PowerShell (Core), using the Windows PowerShell compatibility feature:
Import-Module -UseWindowsPowerShell PackageManagement.}

^{[2] As shown in your question, they are stored in the HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall (64-bit applications) and HKEY_LOCAL_MACHINE\Wow6432Node \Software\Microsoft\Windows\CurrentVersion\Uninstall (32-bit applications) registry keys.}

Or for example:

get-package *chrome* | uninstall-package