--Write only the url or model. (Only url is described this time)
Before editing
erb:_form.html.erb
<%= form_with(model: @set, url: "/sets/create", local: true) do |f| %>
<div class="form-title">
<%= f.label :title, "title" %>
<%= f.text_field :title %>
</div>
<% end %>
After editing
erb:_form.html.erb
<%= form_with(url: "/sets/create", local: true) do |f| %>
<div class="form-title">
<%= f.label :title, "title" %>
<%= f.text_field :title %>
</div>
<% end %>