Flash alert Error not displaying Rails - ruby-on-rails

Question

So I have two flash notice that should appear one if a post is saved successfully and another if there is an error creating a new post . I implemented it a while back but I just realized that the error flash isn't being displayed properly. All it displays is a red empty notice on top of the window, while the notice for a "successful save" does appear correctly.
for my controller i have :
def create
#topic = Topic.new
#topic.name = params[:topic][:name]
#topic.description = params[:topic][:description]
#topic.public = params[:topic][:public]
if #topic.save
redirect_to #topic, notice: "Topic was saved successfully."
else
flash.now[:alert] = "Error creating topic. Please try again."
render :new
end
end
new post view :
<div class="col-md-8">
<%= render partial: 'form', locals: { topic: #topic, post: #post } %>
</div>
</div>
_form.html:
<%= form_for [topic, post] do |f| %>
<% if post.errors.any? %>
<div class="alert alert-denger">
<h4><%= pluralize(post.errors.count, "error") %>.</h4>
<ul>
<% post.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<%= form_group_tag(post.errors[:title]) do %>
<%= f.label :title %>
<%= f.text_field :title, class: 'form-control', placeholder: "Enter post title" %>
<% end %>
<%= form_group_tag(post.errors[:body]) do %>
<%= f.label :body %>
<%= f.text_area :body, rows: 8, class: 'form-control', placeholder: "Enter post body" %>
<% end %>
<div class="form-group">
<%= f.submit "Save", class: 'btn btn-success' %>
</div>
<% end %>

Answer 1

Please put this in application.html.erb file.
<% flash.each do |key, value| %>
<div class="flash <%= key %>"><%= value %></div>
<% end %>

Answer 2

Try to add flash massages in your application.html.erb:
<% flash.each do |key, value| %>
<div class="alert alert-<%= key %>">
<%= value %>
</div>
<% end %>
usually it put above <%= yield %>