We recently released a security update to W3 Total Cache that addresses a vulnerability that can be exploited on misconfigured servers when database caching to disk is enabled. All users are encouraged to update.
If you see the following error following the upgrade: Fatal error: Call to undefined function w3_is_dbcluster() in /path/to/wp-content/some-file.php
This likely means that you’ve had us configure W3 Total Cache on your site already, and you were running a newer version of the plugin already.
You’ll need to manually disable W3 Total Cache to restore access and reach out so we can get you sorted.