Exception Notification Missing rack.input

When I am trying to use Exception Notification plugin in my Rails 3
project, I am getting this error.

Missing rack.input

this error is occurring in

/vendor/plugins/exception_notification/lib/exception_notifier/views/exception_notifier/_request.text.erb
at line 3

This is the _request.text.erb file

1: * URL : <%= raw @request.url %>
2: * IP address: <%= raw @request.remote_ip %>
3: * Parameters: <%= raw @request.filtered_parameters.inspect %>
4: * Rails root: <%= raw Rails.root %>

I have not over ridden this anywhere in my app. please help. Stuck here
in this error for one full day