Are you using a customer logger?
Check in config/environments/development.rb
. That's where the logger is usually assigned.
Also, look in config/initializers
for logging-related monkey patches.
I was using Chris Powell's logger patch, and it caused a very similar error.
If you're using that patch, there's an updated one for Rails 4: http://cbpowell.wordpress.com/2013/08/09/beautiful-logging-for-ruby-on-rails-4/