Failed to download file in File Manager (Plesk Control Panel->subscriptions->domain.tld->File Manager->download some file). The following error appears:
Fatal error: Call to undefined method FileManager::popen_wrapper() in C:\Program Files (x86)\Parallels\Plesk\admin\plib\ui_common\FileManagerUIPointer.php on line 950
Internal issue PPPM-2125.
Issue is completely solved in Plesk 11.0.9 MU#63, please make sure that microupdate is installed.