Started GET "/apple-touch-icon.png" for ::1 at 2015-02-08 16:46:28 -0600
ActionController::RoutingError (No route matches [GET] "/apple-touch-icon.png"):
web-console (2.0.0) lib/action_dispatch/debug_exceptions.rb:22:in `middleware_call'
web-console (2.0.0) lib/action_dispatch/debug_exceptions.rb:13:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.2.0) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.2.0) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.2.0) lib/active_support/tagged_logging.rb:68:in `block in tagged'
activesupport (4.2.0) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (4.2.0) lib/active_support/tagged_logging.rb:68:in `tagged'
railties (4.2.0) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.6.0) lib/rack/methodoverride.rb:22:in `call'
rack (1.6.0) lib/rack/runtime.rb:18:in `call'
activesupport (4.2.0) lib/active_support/cache/strategy/local_cache_middleware.rb:28:in `call'
rack (1.6.0) lib/rack/lock.rb:17:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/static.rb:113:in `call'
rack (1.6.0) lib/rack/sendfile.rb:113:in `call'
railties (4.2.0) lib/rails/engine.rb:518:in `call'
railties (4.2.0) lib/rails/application.rb:164:in `call'
rack (1.6.0) lib/rack/lock.rb:17:in `call'
rack (1.6.0) lib/rack/content_length.rb:15:in `call'
rack (1.6.0) lib/rack/handler/webrick.rb:89:in `service'
/Users/Raphel/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/webrick/httpserver.rb:138:in `service'
/Users/Raphel/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/webrick/httpserver.rb:94:in `run'
/Users/Raphel/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/webrick/server.rb:294:in `block in start_thread'
Rendered /Users/Raphel/.rvm/gems/ruby-2.2.0/gems/web-console-2.0.0/lib/action_dispatch/templates/rescues/_trace.html.erb (1.5ms)
Rendered /Users/Raphel/.rvm/gems/ruby-2.2.0/gems/web-console-2.0.0/lib/action_dispatch/templates/routes/_route.html.erb (0.8ms)
Rendered /Users/Raphel/.rvm/gems/ruby-2.2.0/gems/web-console-2.0.0/lib/action_dispatch/templates/routes/_table.html.erb (1.9ms)
Rendered /Users/Raphel/.rvm/gems/ruby-2.2.0/gems/web-console-2.0.0/lib/action_dispatch/templates/rescues/_request_and_response.html.erb (1.1ms)
Rendered /Users/Raphel/.rvm/gems/ruby-2.2.0/gems/web-console-2.0.0/lib/action_dispatch/templates/rescues/_web_console.html.erb (1.2ms)
Rendered /Users/Raphel/.rvm/gems/ruby-2.2.0/gems/web-console-2.0.0/lib/action_dispatch/templates/rescues/routing_error.html.erb within rescues/layout (83.4ms)
尝试将图像放在app/assets/images目录中，然后重新启动服务器。
更新
以下是如何包含apple touch图标。。。
app/layouts/application.html.erb
<head>
<%= favicon_link_tag "apple-touch-icon-100.png",
rel: "apple-touch-icon",
sizes: "100x100",
type: "image/png" %>
</head>
确保apple-touch-icon-100.png存在于app/assets/images目录中。