Error when attempting to copy inherited permissions

Question

I wish to disable ACL inheritance on a group of subfolders, while retaining existing permissions.

To this end, I'm running this snippet:

gci | % {
  $Acl = Get-Acl $_
  $Acl.SetAccessRuleProtection($true, $true)
  Set-Acl $_ $Acl
}

For each subfolder, an error occurs:

Set-Acl : Cannot set the ACL because the method that it needs to invoke, SetSecurityDescriptor, does not exist.

I found this similar question, but it's not quite an exact duplicate. OP intends to clear all permissions; I would like to retain them.

Also: OP states "I got rid of the error message," but doesn't reveal how he managed to do so

How can I use PowerShell to accomplish this?

Answer 1

There are a number of problems with Set-Acl. I typically try to rely on .NET for ACL work:

try {
    $FileSystemObject = (Get-Item '.\accessibilitycpl.dll')
    $Acl = $FileSystemObject.GetAccessControl()
    $Acl.SetAccessRuleProtection($true,$false)
    $FileSystemObject.SetAccessControl($Acl)
} catch {
    ## Catch exceptions!
}