app/views/shared/_error_messages.html.erb
<% if object.errors.any? %>
<div id="error_explanation">
<div class="alert alert-error">
<%= t('helpers.forms.errors') %> <%= pluralize(object.errors.count, t("helpers.forms.error")) %>.
</div>
<ul>
<% object.errors.full_messages.each do |msg| %>
<li>* <%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="validation-error"></div>