[Plugin: W3 Total Cache] file is not write-able

Hey,
just upgraded to 3.4 and getting this error

The settings could not be saved because the configuration file is not write-able. Please run chmod 777 /var/www/vhosts/mysite/httpdocs/wp-content/w3-total-cache-config.php

the problem is the file is set to 777. Anyone else having this issue?

Cheers

https://www.ads-software.com/extend/plugins/w3-total-cache/