Steps

The following steps demostrate how to re-produce the NameError.

Setup Env

1. Clone the project

git clone https://github.com/acenqiu/name_error_test.git

2. Bundle install & Create the production database

bundle install
rake db:create RAILS_ENV=production

3. Run the production console to check everything is right

rails console production

Reproduce

comment out one line in application_controller.rb, and it should raise the NameError

Edit the file application_controller.rb, comment out following line.

# rescue_from ActiveRecord::RecordInvalid, with: :show_errors

Run the production console again.

rails c production

And you should see the error raised.

~/Documents/name_error_test/app/controllers/application_controller.rb:6:in `<class:ApplicationController>': uninitialized constant ActiveRecord::RecordInvalid (NameError)

What I know

If we disable eager_load in production.rb, everything is fine, but this is not what I want. No matter which action controller I put the rescue_from ActiveRecord::RecordInvalid in, the error still exists.

rescue_from ActiveRecord::RecordNotFound will survive from this error.