Not Found The requested URL /blog/ was not found on this server.

[Etienne-C]

I installed the gem and add this code in my config/application.rb

class Application < Rails::Application
config.middleware.insert(0, Rack::ReverseProxy) do
reverse_proxy_options preserve_host: true
reverse_proxy /^/blog(/?.*)$/, 'http://exemple.com'
end
end

When I visit the page "mysite.com/blog" this message appear: "Not Found The requested URL /blog/ was not found on this server."

Any idea? (My site is hosted on Heroku)
Thx