Redmine

I am not sure how this happens and I can't reproduce it on my test version, but its persistent on my production system

Anonymous users do not have access to wiki pages. On my home screen I have links to some of the wikis and when you are not logged in, clicking on such link rises Internal Error. The production log shows only this:

NoMethodError (undefined method `title' for nil:NilClass):
  app/controllers/application_controller.rb:193:in `require_login'
  app/controllers/application_controller.rb:215:in `deny_access'
  app/controllers/application_controller.rb:227:in `authorize'

If this is not a bug, I would appreciate any help in managing it.