My new rails application won’t display the “Yay!” page!

I was doing some recent environment testing with rails with the same application created on each of OSX, CentOS, and Ubuntu and was surprised when the application gave an error about no root route available, instead of the “Yay!” page:


I, [2020-02-12T16:51:06.845723 #46720] INFO -- : [8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] Started GET "/" for 127.0.0.1 at 2020-02-12 16:51:06 -0800
F, [2020-02-12T16:51:06.846251 #46720] FATAL -- : [8d1ab83a-b4e4-45bf-a734-a6494c4d15c2]
F, [2020-02-12T16:51:06.846316 #46720] FATAL -- : [8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] ActionController::RoutingError (No route matches [GET] "/"):
F, [2020-02-12T16:51:06.846353 #46720] FATAL -- : [8d1ab83a-b4e4-45bf-a734-a6494c4d15c2]
F, [2020-02-12T16:51:06.846390 #46720] FATAL -- : [8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] actionpack (5.2.4.1) lib/action_dispatch/middleware/debug_exceptions.rb:65:in `call'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] actionpack (5.2.4.1) lib/action_dispatch/middleware/show_exceptions.rb:33:in `call'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] railties (5.2.4.1) lib/rails/rack/logger.rb:38:in `call_app'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] railties (5.2.4.1) lib/rails/rack/logger.rb:26:in `block in call'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] activesupport (5.2.4.1) lib/active_support/tagged_logging.rb:71:in `block in tagged'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] activesupport (5.2.4.1) lib/active_support/tagged_logging.rb:28:in `tagged'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] activesupport (5.2.4.1) lib/active_support/tagged_logging.rb:71:in `tagged'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] railties (5.2.4.1) lib/rails/rack/logger.rb:26:in `call'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] actionpack (5.2.4.1) lib/action_dispatch/middleware/remote_ip.rb:81:in `call'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] actionpack (5.2.4.1) lib/action_dispatch/middleware/request_id.rb:27:in `call'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] rack (2.2.2) lib/rack/method_override.rb:24:in `call'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] rack (2.2.2) lib/rack/runtime.rb:22:in `call'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] activesupport (5.2.4.1) lib/active_support/cache/strategy/local_cache_middleware.rb:29:in `call'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] actionpack (5.2.4.1) lib/action_dispatch/middleware/executor.rb:14:in `call'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] rack (2.2.2) lib/rack/sendfile.rb:110:in `call'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] railties (5.2.4.1) lib/rails/engine.rb:524:in `call'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] puma (3.12.2) lib/puma/configuration.rb:227:in `call'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] puma (3.12.2) lib/puma/server.rb:674:in `handle_request'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] puma (3.12.2) lib/puma/server.rb:476:in `process_client'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] puma (3.12.2) lib/puma/server.rb:334:in `block in run'
[8d1ab83a-b4e4-45bf-a734-a6494c4d15c2] puma (3.12.2) lib/puma/thread_pool.rb:135:in `block in spawn_thread'


I had assumed that any new rails application would serve out the, every so happy, “Yay!” page, regardless of environment. It turns out not to be the case. To fix the issue, set the RAILS_ENV to development and restart the rails server:


> RAILS_ENV=development rails server
=> Booting Puma
=> Rails 5.2.4.1 application starting in development
=> Run `rails server -h` for more startup options
Puma starting in single mode...
* Version 3.12.2 (ruby 2.6.0-p0), codename: Llamas in Pajamas
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://localhost:3000
Use Ctrl-C to stop


Easy fix!