Note that the error is in UsersController#show so it is nothing to do
with show.html.erb as it has not got there yet. Since all you are
doing in show is finding a record by id and the error says that the
record was not found it seems likely that the error is with
params[:id]. Have a look in development.log and see what parameters
are being passed to show.
ActiveRecord::RecordNotFound (Couldn't find User without an ID):
E:/Rails_instanT/ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/base.rb:1364:in
`find_from_ids'
E:/Rails_instanT/ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/base.rb:541:in
`find'
/app/controllers/users_controller.rb:3:in `show'
Can you not see the problem? There is no id in the parameters.
Given that it is not surprising that User.find(params[:id]) fails
saying that there is no id.