Error in Benchmark.rb

I suddently started getting this on an action that previously worked:

NoMethodError in Accounts#discover

You have a nil object when you didn’t expect it!
The error occured while evaluating nil.real

RAILS_ROOT: .
Application Trace | Framework Trace | Full Trace

#{RAILS_ROOT}usr/local/lib/ruby/gems/1.8/gems/actionpack-1.10.2/lib/action_c
ontroller/benchmarking.rb:69:in perform_action_without_rescue' #{RAILS_ROOT}usr/local/lib/ruby/gems/1.8/gems/actionpack-1.10.2/lib/action_c ontroller/rescue.rb:82:inperform_action’
#{RAILS_ROOT}usr/local/lib/ruby/gems/1.8/gems/actionpack-1.10.2/lib/action_c
ontroller/base.rb:365:in send' #{RAILS_ROOT}usr/local/lib/ruby/gems/1.8/gems/actionpack-1.10.2/lib/action_c ontroller/base.rb:365:inprocess_without_session_management_support’
#{RAILS_ROOT}usr/local/lib/ruby/gems/1.8/gems/actionpack-1.10.2/lib/action_c
ontroller/session_management.rb:116:in `process’

Any ideas?