I am using a simple redirect after a user logs in so they can get to the page they were heading too the URLs were ending up with %2F in the url which caused a 404 error. The problem wasn’t actually in Grails at all but in the mod_rewrite rule being used to force HTTPS connection the rule was set up to end with [L,R] when to correctly deal with the url encoding we were already doing it needed to be [NE,L,R]

Reference: http://www.webmasterworld.com/apache/3279075.htm