ActionController::RoutingError (No route matches [GET] “/favicon.ico”) in Rails

You’re getting this error because you don’t have a favicon.ico in your public/ directory of your application. Because the file doesn’t exist there, Rails moves on, looking for a route to match against /favicon.ico in the config/routes.rb.

You can fix this in one of two ways

1. Manually place the favicon.ico file in the public/ directory of your application.

2. Put the favicon.ico in app/assets/images/ and then change your <link ... tag to use image_path

   <link href="https://stackoverflow.com/questions/15687506/<%= image_path("favicon.ico") %>" rel="shortcut icon" />
   

   This will place the favicon.ico in public/assets/favicon.ico, not in the document root.

I suggest sticking with #1 above.

As for why this request is even showing up in your logs, many modern browsers look in the root of the domain for /favicon.ico to use for bookmarking, or presentation in a tab or the address bar. This is why it’s a good idea to keep the favicon.ico in the root of your domain, in case a browser decides (for whatever reason) to ignore your <link rel="icon shortcut" ... tag.