Add remote: => true on Form_for

You've inserted the :remote = true right AFTER the parameter list. Just leave off the parenthesis.

<%= form_for @document, :remote => true do |f| %> 

<%= form_for(@document, :remote => true) do |f| %>
  ...
<% end %>

reefer this : http://apidock.com/rails/ActionView/Helpers/FormHelper/form_for