We had experienced that error
It was produced when accessing directly to wp-postviews.php, in our case it was a bot (we think a fake GoogleBot).
At webserver level, with Apache we can avoid direct accessing, placing an .htaccess file inside wp-content directory.
Order deny,allow
Deny from all
<Files ~ “.(xml|css|jpe?g|png|gif|js)$”>
Allow from all
</Files>
This configuration could also be done in the main conf file for the domain or the whole server.
If server has memory and processing power enough, it could be good to use firewall rules (iptables) to avoid this request to reach Apache
What do you think about this approach?