Error redux-framework

Hello,

I bought and installed the theme … installing all the plugins I get this error:

Fatal error: Call to a member function put_contents() on null in /home/artigian/public_html/agenziawebtorino.org/zamy/wp-content/plugins/redux-framework/ReduxCore/inc/class.redux_filesystem.php on line 233

how can I fix it?
Thanks
Best regards