ActiveRecord::AdapterNotSpecified database configuration does not specify adapter

Question

When I use heroku open my web app works fine but when I\'m using rails s (localhost) I am running into this error:

ActiveRecord::AdapterNotSpecified database         


        

Answer 1

In my case the reason was in my Rakefile.

when I run rake db:migrate, I got this:

rake db:migrate
rake aborted!
ActiveRecord::AdapterNotSpecified: The `default_env` database is not configured for the `default_env` environment.

Available databases configurations are:

development
test
production

I've found this row in my Rakefile:

ActiveRecord::Base.establish_connection(ENV['DATABASE_URL'])

and changed with default value: ActiveRecord::Base.establish_connection(ENV['DATABASE_URL'] || 'postgres://localhost/db_name')

and now it works fine. Details you can find here