If you get this error when you try to start your grails app:
Caused by: java.lang.ClassNotFoundException: sun.tools.native2ascii.Main
Copying %Java_Home%/lib/tools.jar to %Java_Home%/jre/lib/ext/tools.jar fixed this problem.
(a better approach is to set up JRE path to the directory JDK, but Oracle is not providing JDK for old versions such as 1.6)