I am currently learning Rails Guides. I went through the steps but still encountered a mistake.
My Ruby version is ruby 2.1.1p76 and the Rails version is
In the render method, plain option was added in Rails 4.1 and you are using Rails 4.0.4. So, rails ignored this option and started looking for a template named articles/create as you are in ArticlesController#create action. Obviously, the template doesn't exist so you get the error Template is missing.
Refer to the discussion on this topic on Github: Introduce render :plain and render :html, make render :body as an alias to render :text
Now, for using the below mentioned syntax you would need to upgrade to Rails 4.1:
render plain: params[:article].inspect
With your current version of Rails 4.0.4, you can go for:
render text: params[:article].inspect