Mapping a url to a view name like this normally works fine:
The "/" pattern is mapped to the "/index" view and the default view resolver will associate that with grails-app/views/index.gsp. If there are multiple view resolvers in the application context Grails currently only tries one of them. This is the case when certain plugins are installed. For example, both the springmvc and freemarker plugins contribute a view resolver to the application context.
The simplest way to recreate the problem is to create a new app and install the springmvc plugin into the app. Start the app and try to access the application root and the view resolution should fail.
A workaround is to be explicit about the view file being rendered, like this: