Solution to "406 Not Acceptable" error 2010-06-10 This problem is arising mainly because of "mod_security"; a web application firewall. All the cPanel hosts use the "mod_security" feature. So What is mod_security? ModSecurity is an embeddable web application firewall. It provides protection from a range of attacks against web applications and allows for HTTP traffic monitoring and real-time analysis with no changes to existing infrastructure. It is also an open source project that aims to make the web application firewall technology available to everyone.   More