Hello nice community! 
I have an error on a client site after updating w3 total cache just a moment ago.
The site was installed using wpfc command, and also has the w3 total cache which I believe was installed by default.
I use memcached for caching resources (from w3tc).
Everything was working fine, but suddenly after updating w3 plugin, the site started to give me HTTP 500. I also updated the wordfence security plugin at the same time. But I noticed the problem is W3 since I renamed the plugin folder and the site now works.
However, I'd like to have W3 working again, since it's a site with too many visitors.
Does anybody know what could be?
Thank you.