no implicit conversion of nil into String

问题

currently I'm trying to set up a simple app in Ruby on Rails. I've migrated the db, seeded it and am now stuck at the following error.

no implicit conversion of nil into String

Extracted source (around line #4):

1: <!--[if lt IE 9]>
2: <script src="http://html5shiv.googlecode.com/svn/trunk/html5.js"></script>
3: <![endif]-->
4: <%= stylesheet_link_tag 'blueprint/screen', :media => 'screen' %>
5: <%= stylesheet_link_tag 'blueprint/print',  :media => 'print' %>
6: <%= stylesheet_link_tag 'custom', :media => 'screen' %>

It seems like the asset tags helpers are not working properly or returning nil (if that's even possible)?

回答1:

I hotfixed this error by adding the following line to my application.rb:

ActionController::Base.config.relative_url_root = ''

The error is most likely due to a bug in my rails version which is 3.0.12.

来源：https://stackoverflow.com/questions/16044008/no-implicit-conversion-of-nil-into-string