The relevant upstream docs say "You can use a dynamic or static page for the handler. If you use a static page, the server will return a 404 HTTP status code with the content of your static page."
http://redmine.lighttpd.net/projects/1/wiki/Server_error-handler-404Details I hope I am reading this wrong, but this would suggest this was known behaviour? http://redmine.lighttpd.net/issues/2456
