Redmine

Redmine info:

Environment:
  Redmine version                3.1.2.stable
  Ruby version                   2.0.0-p481 (2014-05-08) [x86_64-linux]
  Rails version                  4.2.4
  Environment                    production
  Database adapter               Mysql2

*The problem occurs only with Apache mod security turned on. *
Redmine log:

Started GET "/500.shtml" for 94.247.200.2 at 2016-01-21 02:51:52 -0500

ActionController::RoutingError (No route matches [GET] "/500.shtml"):
  actionpack (4.2.4) lib/action_dispatch/middleware/debug_exceptions.rb:21:in `call'
  actionpack (4.2.4) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
  railties (4.2.4) lib/rails/rack/logger.rb:38:in `call_app'
  railties (4.2.4) lib/rails/rack/logger.rb:20:in `block in call'
  activesupport (4.2.4) lib/active_support/tagged_logging.rb:68:in `block in tagged'
  activesupport (4.2.4) lib/active_support/tagged_logging.rb:26:in `tagged'
  activesupport (4.2.4) lib/active_support/tagged_logging.rb:68:in `tagged'
  railties (4.2.4) lib/rails/rack/logger.rb:20:in `call'
  actionpack (4.2.4) lib/action_dispatch/middleware/request_id.rb:21:in `call'
  rack (1.6.4) lib/rack/methodoverride.rb:22:in `call'
  rack (1.6.4) lib/rack/runtime.rb:18:in `call'
  activesupport (4.2.4) lib/active_support/cache/strategy/local_cache_middleware.rb:28:in `call'
  actionpack (4.2.4) lib/action_dispatch/middleware/static.rb:116:in `call'
  rack (1.6.4) lib/rack/sendfile.rb:113:in `call'
  railties (4.2.4) lib/rails/engine.rb:518:in `call'
  railties (4.2.4) lib/rails/application.rb:165:in `call'
  railties (4.2.4) lib/rails/railtie.rb:194:in `public_send'
  railties (4.2.4) lib/rails/railtie.rb:194:in `method_missing'
  passenger (4.0.45) lib/phusion_passenger/rack/thread_handler_extension.rb:74:in `process_request'
  passenger (4.0.45) lib/phusion_passenger/request_handler/thread_handler.rb:141:in `accept_and_process_next_request'
  passenger (4.0.45) lib/phusion_passenger/request_handler/thread_handler.rb:109:in `main_loop'
  passenger (4.0.45) lib/phusion_passenger/request_handler.rb:448:in `block (3 levels) in start_threads'

Content causing the issue:
[[http://apaste.info/rA2]]