Cache system enable shows blank page again

Recently, I have updated my site to WordPress version 4. Now whenever I do enable WP Fatest cache it shows blank page on site.

I found it happens due to below reason:

After update to WordPress version 4 it started giving me below error:

Notice: ob_end_flush(): failed to delete buffer zlib output compression in
/hermes/bosnaweb04a/b1195/mysite/wordpress/wp-includes/functions.php on line 3092

To disable above Notification I have modified and commented out below part in functions.php page as below:

function wp_ob_end_flush_all() {
$levels = ob_get_level();
//for ($i=0; $i<$levels; $i++)
//ob_end_flush();
}

When I do comment out above part WP Fastest Cache doesn’t work.

Would you please assist what is the solution?

Thank you so much.

https://wordpress.org/plugins/wp-fastest-cache/