This emerged through reports of problems with the feeds plugin. If you install the feeds plugin into an app, you cannot have a controller called "feed" because the taglib from the plugin is in the "feed" namespace - you get an exception: java.lang.ClassCastException: org.codehaus.groovy.grails.web.taglib.NamespacedTagDispatcher at org.codehaus.groovy.grails.web.servlet.mvc.SimpleGrailsControllerHelper.executeAction(SimpleGrailsControllerHelper.java:382) at org.codehaus.groovy.grails.web.servlet.mvc.SimpleGrailsControllerHelper.handleURI(SimpleGrailsControllerHelper.java:237) at org.codehaus.groovy.grails.web.servlet.mvc.SimpleGrailsControllerHelper.handleURI(SimpleGrailsControllerHelper.java:153) at org.codehaus.groovy.grails.web.servlet.mvc.SimpleGrailsController.handleRequest(SimpleGrailsController.java:88) at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:48