Yes, it it true.
See Link: http://www.uscis.gov/news/alerts/uscis-revises-form-n-400-application-naturalization
www.uscis.gov/news/alerts/uscis-revises-form-n-400-application-naturalization
On Monday, May 5, 2014, USCIS will no longer accept older versions of Form N-400. USCIS will reject and return previous versions of Form N-400 submitted after May 5, 2014.
See Link: http://www.uscis.gov/news/alerts/uscis-revises-form-n-400-application-naturalization
www.uscis.gov/news/alerts/uscis-revises-form-n-400-application-naturalization
On Monday, May 5, 2014, USCIS will no longer accept older versions of Form N-400. USCIS will reject and return previous versions of Form N-400 submitted after May 5, 2014.