Finally, after spending a considerable amount of time trying get ride of this ugly error while I’m trying to create my first Grails application:

Welcome to Grails 0.5 - http://grails.org/

Licensed under Apache Standard License 2.0

Grails home is set to: D:\GrailsBase Directory: D:\GrApp

Environment set to production

Note: No plugin scripts found

Running script D:\Grails\scripts\CreateApp.groovy

Error executing script CreateApp: Cannot invoke method addURL() on null object

java.lang.NullPointerException: Cannot invoke method addURL() on null object

at org.codehaus.groovy.runtime.NullObject.invokeMethod(NullObject.java:1

05)

at org.codehaus.groovy.runtime.Invoker.invokePogoMethod(Invoker.java:148

)

at org.codehaus.groovy.runtime.Invoker.invokeMethod(Invoker.java:110)

at org.codehaus.groovy.runtime.InvokerHelper.invokeMethod(InvokerHelper.

..........

Mr. Graeme Rocher came to rescue.
So, if you have GROOVY_HOME environment variable defined in your system and and you got that ugly error while you are trying to run Grails scripts, then remove the GROOVY_HOME environment variable.
Maybe you don’t want to remove it completely, you can just “remove” it from your current console.
In MS Windows, you can use :
set %GRAILS_HOME%=
Enjoy your search of the Grails!