Forum OpenACS Q&A: Response to broken ns_returnnotfound and templated error return pages

Are 404s from requests for *.tcl pages handled differently from 404s for *.html and *.adp pages in OACS 4.5? They are in 3.2.5:
  • a 404'd .html or .adp request will get the file (say, /global/file-not-found.html) specified by ns_param NotFoundResponse
  • a 404'd .tcl request, however, does not; in /tcl/ad-aolserver-3.tcl.preload, there's an ns_register_proc that sends all requests to ns_sourceproc which tries to source the file and calls ns_returnnotfound directly if it fails. In the AOLServer api (, there doesn't appear to be any way to intervene in ns_returnnotfound to tart up what the user sees beyond the stark "Not Found" message.
The problem for a heavily .tcl site is that if you're not sending out .html or .adp files, your templated page doesn't go out like you want.

Did you hack ns_sourceproc (or replace it entirely in the new request processor schema) in order to create uniform system behavior in these two cases? Or is there some benefit to having AOLServer deliver two different kinds of 404s?