create with has_many through association gets NoMethodError (undefined method `name' for nil:NilClass)

Question

I\'m doing this tutorial and am stuck in the Tagging part. Basically I have articles that can have a list of tags. As one article can has multiple tags and vice versa, there

Answer 1

Upgrade to Rails 4.0.13 (or later) or downgrading to Ruby 2.1.1 solves the problem.