No such middleware to insert before: ActionDispatch::Static

[dankmitchell]

Deploying to heroku in prod can me this error No such middleware to insert before: ActionDispatch::Static so removed this gem and the deploy was successful.

ruby '2.4.0'
gem 'rails', '5.0.2'

[raul]

As the message says, the ActionDispatch::Static middleware must be missing in your app.

That middleware is included unless config.public_file_server.enabled is false. That config value is calculated this way, so you may want to set a configuration variable named RAILS_SERVE_STATIC_FILES to true.