Powershell: updating actions of MS Windows scheduled tasks that run on remote servers

update-remote-scheduled-task-action.ps1

<#
 # Updating actions of existing, known scheduled tasks to the newest known application version.
 # The script assumes that each task has exactly 1 action. Other actions will get deleted.
 #
 # Author: A.E.Veltstra
 # Version: 2.23.607.1200
 #>

# List all remote servers to be processed.
$hosts = @{
    "host-name" = @(
        "\scheduled\task\path\*"
    )
};

# Buffer to collect any errors during processing.
$errors = @();

# determine what part of the task action needs to be updated
$old_date = "2.23.530.1550";
$new_date = "2.23.615.1213";

<#
    NOTE: Merely asking for the credential input WILL FAIL.
    For whatever reason, the UserName and Password of the regular credential object WILL CAUSE lock-out.
    Instead, we MUST elevate to the NetworkCredential.
#>
# (Tech note: we cannot use the variable name 'pwd' as that already is used by Powershell as the present working directory.)
$cred = (Get-Credential -Message "What network user name and pwd should the updated tasks run as?").GetNetworkCredential();

# Processing each host
# (Tech note: we cannot use the variable name 'host' as that is reserved by Powershell.)
foreach($h in $hosts.Keys) {
    if (Test-Connection -ComputerName $h -Quiet -ErrorAction SilentlyContinue) {
        $c = New-CimSession -ComputerName $h -ErrorAction SilentlyContinue;
        $hosts[$h] | %{
            $taskpath = $_;
            $tasks = Get-ScheduledTask -CimSession $c -TaskPath $taskpath;
            $tasks | %{
                $old_action = $_.Actions[0];
                if ($old_action.Execute.Contains($old_date) -or $old_action.WorkingDirectory.Contains($old_date)) {
                    #$old_action | echo;
                    $new_action = New-ScheduledTaskAction `
                        -Argument $old_action.Arguments `
                        -WorkingDirectory $old_action.WorkingDirectory.replace($old_date, $new_date) `
                        -Execute $old_action.Execute.replace($old_date, $new_date);
                    #$new_action | echo;
                    if ($_.Triggers) {
                        Set-ScheduledTask -CimSession $c `
                            -TaskPath $_.TaskPath `
                            -TaskName $_.TaskName `
                            -Action $new_action `
                            -Trigger $_.Triggers `
                            -User $cred.UserName `
                            -Password $cred.Password;
                    } else {
                        Set-ScheduledTask -CimSession $c `
                            -TaskPath $_.TaskPath `
                            -TaskName $_.TaskName `
                            -Action $new_action `
                            -User $cred.UserName `
                            -Password $cred.Password;
                    }
                } else {
                    "Not updating: no date match." | echo;
                    $_.TaskName | echo;
                    $old_action.Execute | echo;
                    $old_action.WorkingDirectory | echo;
                }
            }
        }
    }
}

Part of the challenge with updating actions in existing scheduled tasks, is that the way Microsoft lets us do this, is less of an update and more of a full replace. That will result in losing some information if it isn't copied explicitly to the new task.