Rails - Aug 2006 - BUG in actionpack , error evaluating nil.downcase ?

hi all,
I try to deploy on my host (site5) on I have this error with 
dispatch.fcgi start !
( RAILS_GEM_VERSION = ''1.1.6'' )

You have a nil object when you didn''t expect it!
The error occured while evaluating nil.downcase
/usr/lib/ruby/gems/1.8/gems/actionpack-1.12.5/lib/action_controller/request.rb:18:in
`method''


any idea ?

arnaud