UPDATE: the web site of QuintoLabs was updated with the latest releases of the product that fix crushing AdBlock module. See http://quintolabs.com/qlicap_download.php for installation packages for version 18.104.22.168bd07. It is recommended to upgrade your installation.
Having the last 1.4.0 edition of QuintoLabs Content Security installed on your Squid proxy you may experience the “ICAP Protocol error” from your browser. The problem here is qlproxy crushes suddenly while doing content filtering of ICAP traffic coming from Squid. And when Squid can not contact the ICAP server it gives users the “ICAP protocol error” page.
We deeply apologize for the error. Crush investigation revealed a problem in AdBlock module… it has been fixed and new build of qlproxy is going to be released today (3rd October 2011). To temporary get rid of the problem, disable AdBlock module in the qlproxyd.conf file. You may also set the
icap_enable directive to
off in your Squid server and restart it if you wish to disable