Malicious users trying to pass extra or modified URL parameters to your templates, in order to gain access to confidential information or exploiting cross-site scripting vulnerabilities . 2 - The second reason is a matter of professionalism. No web site should ever display ugly error templates. Instead it should try to recover gracefully and alert the web site administrator, so that the error can be fixed. 3 - The third reason is security.
Error messages are pure gold for hackers.
They contain precious debugging information such as file paths and invalid SQL statements that could be reversed-engineered against the site. This tag is used in your application.cfm file and points at templates that will customize the error messages returned by ColdFusion. In the following pages, we will learn how to use both techniques.