My team was provisioning a ruby on rails application on a new Operating System with different ruby and client libraries and we came across a strange bug.

Intermittently we were seeing the failures in the application with the following messages in the passenger log:

NoMethodError: undefined method `each' for nil:NilClass

and

(NoMethodError) "undefined method `each' for nil:NilClass"

/usr/local/rvm/gems/ruby-1.9.2-p0/ruby/1.9.1/gems/mysql2-0.2.4/lib/active_record/connection_adapters/mysql2_adapter.rb:628:in `select'
/usr/local/rvm/gems/ruby-1.9.2-p0/ruby/1.9.1/gems/activerecord-3.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:7:in `select_all'
/usr/local/rvm/gems/ruby-1.9.2-p0/ruby/1.9.1/gems/activerecord-3.0.0/lib/active_record/connection_adapters/abstract/query_cache.rb:54:in `block in select_all' …