Make sure assets in ./vendor are precompiled

config/environments/production.rb

@@ -31,6 +31,7 @@ Huginn::Application.configure do
 
   # Generate digests for assets URLs
   config.assets.digest = true
+  config.assets.precompile += %w(*.png *.jpg *.jpeg *.gif)
 
   # Specifies the header that your server uses for sending files.
   # config.action_dispatch.x_sendfile_header = "X-Sendfile" # for apache