The Security Token Service must have mappings set for Java servlet pages.

Resource mapping is the process of tying a particular file type to a process in the web server that can serve that type of file to a requesting client and identify which file types are not to be delivered to a client. By not specifying which files can and cannot be served to a user, the web server could deliver to a user web server configuration files, log files, password files, etc. As Tomcat is a Java-based web server, the main file extension used is *.jsp. This check ensures the *.jsp and *.jspx file types have been properly mapped to servlets.