Maybe I'm doing something wrong, but I could not find any mention of this in the documentation.

When using the internal cgi-bin engine of Tomcat 4 (org.apache.catalina.servlets.CGIServlet), the SiteMesh filter throws a NullPointerException.

This happens when requesting anything from the cgi-bin directory (not nesessarily the actual cgi script, any request to the dir produces the error below).

java.lang.NullPointerException
        at com.opensymphony.module.sitemesh.filter.PageResponseWrapper.getPage(PageResponseWrapper.java:263)
        at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:147)
        at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:58)