fix error

app/controllers/announcements_controller.rb

@@ -497,7 +497,7 @@ class AnnouncementsController < ApplicationController
   end
   def get_file
     @url = request.path
-    render :text => "Path not allow",:status => 404 and return if @url.match(/\/\.\./)
+    render :file => "#{Rails.root}/app/views/errors/404.html", :layout => false, :status => :not_found, :content_type => 'text/html' and return if @url.match(/\/\.\./)
     begin
       file = BulletinFile.find(params[:id])
       if File.basename(file.file.path) != URI.decode(params[:f_name])