Modules extracted from core can contain legacy Struts framework Action implementations.
These were possible to call as portal Struts actions using /c prefix, for example /c/wiki/get_page_attachment
However, after extracting from core, these URLs don't work anymore because OSGi module struts configuration is separate from portal struts configuration and portal struts framework cannot find them.
It's important to review all extracted modules and :
1, rewrite all these actions into portlet struts actions
2, rewrite URLs to use portlet URLs / module Struts (/o/wiki-web/c/wiki/get_page_attachment?.....)