PySide / Pyqt qpa_plugin error solved(Or not working QApplication)

if error occurs,

env = os.environ
env.setdefault("QT_DEBUG_PLUGINS","1")
env.setdefault("QT_PLUGIN_PATH", os.getcwd())

set environment variable QT_DEBUG_PLUGINS to True and check the displayed error message.

if error occurs when calling dll in platforms folder, it is the error for QT_PLUGINS. so set the folder and copy the file to current script folder and running it would be clearly solved the errors.