我正在尝试使用rails升级程序gem将rails 2应用程序升级到rails3，但启动服务器显示以下错误，可能是什么原因
$bundle exec rails server
/home/user/.rvm/gems/ruby-1.8.7-head/gems/haml-4.0.5/lib/haml/parser.rb:86: warning: regexp has invalid interval
DEPRECATION WARNING: RAILS_ENV is deprecated. Please use ::Rails.env. (called from /home/user/projects/fedena/config/application.rb:5)
=> Booting Mongrel
=> Rails 3.0.9 application starting in development on http://127.0.0.1:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
Exiting
/home/user/.rvm/gems/ruby-1.8.7-head/gems/activesupport-3.0.9/lib/active_support/core_ext/module/introspection.rb:70:in `const_get': uninitialized constant ActionView::ActionViewError (NameError)
from /home/user/.rvm/gems/ruby-1.8.7-head/gems/activesupport-3.0.9/lib/active_support/core_ext/module/introspection.rb:70:in `local_constants'
from /home/user/.rvm/gems/ruby-1.8.7-head/gems/activesupport-3.0.9/lib/active_support/core_ext/module/introspection.rb:70:in `each'
from /home/user/.rvm/gems/ruby-1.8.7-head/gems/activesupport-3.0.9/lib/active_support/core_ext/module/introspection.rb:70:in `local_constants'
from /home/user/.rvm/gems/ruby-1.8.7-head/gems/activesupport-3.0.9/lib/active_support/core_ext/module/introspection.rb:68:in `each'
from /home/user/.rvm/gems/ruby-1.8.7-head/gems/activesupport-3.0.9/lib/active_support/core_ext/module/introspection.rb:68:in `local_constants'
from /home/user/.rvm/gems/ruby-1.8.7-head/gems/activesupport-3.0.9/lib/active_support/core_ext/module/introspection.rb:86:in `local_constant_names'
from /home/user/projects/fedena/config.ru:3
from /home/user/.rvm/gems/ruby-1.8.7-head/gems/rack-1.2.8/lib/rack/builder.rb:46:in `instance_eval'
from /home/user/.rvm/gems/ruby-1.8.7-head/gems/rack-1.2.8/lib/rack/builder.rb:46:in `initialize'
from /home/user/projects/fedena/config.ru:1:in `new'
from /home/user/projects/fedena/config.ru:1