Method not allowed rails - ruby-on-rails

Question

I am making an ajax post call to a controller. My Ajax call is:
$.ajax({
type:'POST',
url:'/chefUI/configure/save_roles',
data:{ app_name: appname, role_list: role_list},...});
My Routes file is:
scope "/chefUI" do
post '/configure/save_roles', to: 'admin#update_app_roles'
end
And my controller has:
def update_app_roles
begin
application_name = params["app_name"]
puts application_name
role_name_list = params["role_list"]
puts role_name_list
if application_name and !role_name_list.empty?
...
And I am getting a 405 Method Not Allowed response. I'm not sure what are the reasons this might happen. Could someone help me figure out what I'm missing here? I don't why my post request is not even reaching my controller.
Update:
Log file
Started GET "/chefUI/configure/app_roles?app_name=MFRH" for 127.0.0.1 at 2015-07-24 15:08:51 +0530 Processing by AdminController#app_roles as */* Parameters: {"app_name"=>"MFRH"} [1m[35mUser Load (1.0ms)[0m SELECT "users".* FROM "users" WHERE "users"."username" = $1 LIMIT 1 [["username", "an9v0s7"]] [1m[36mApplication Load (2.0ms)[0m [1mSELECT "applications".* FROM "applications" WHERE (lower(app_name) = 'mfrh') ORDER BY "applications"."id" ASC LIMIT 1[0m [1m[35mRole Load (1.0ms)[0m SELECT "roles".* FROM "roles" INNER JOIN "application_roles" ON "roles"."id" = "application_roles"."role_id" WHERE "application_roles"."application_id" = $1 ORDER BY roles.name ASC [["application_id", 1]] Completed 200 OK in 217ms (Views: 0.0ms | ActiveRecord: 5.0ms)
Started POST "/chefUI/configure/save_roles" for 127.0.0.1 at 2015-07-24 15:08:57 +0530
Another Update:
I just found out that I'm getting that response for all my post requests. They were all working before, I created a bunch on new models and suddenly none of them are working.

Answer 1

This problem is a bit deeper than thought before.
Rails does not like when a route path and the asset directory are in the same subdirectory.
When making a post request, you will get method not allowed. The problem is there can be no overlap with paths and the asset directory. The problem is specifically with POST requests in that path. I am assuming somewhere in rails, they must have disabled all non-GET requests for the assets directory.
scope "/chefUI" do
post '/configure/save_roles', to: 'admin#update_app_roles'
end
config.assets.prefix="/chefUI/assets"
^ You need this part so they don't overlap.
In this very simple app below, you will get a method not allowed error. Because the path /welcome is being used for a route and for an asset prefix.
File: config/environment/development.rb
config.assets.prefix = '/welcome'
File: config/routes.rb
resources :welcomes, path: 'welcomes', only: ['index', 'create']
File: app/controllers/welcomes_controller.rb
class WelcomesController < ApplicationController
def index
#welcome = 'hello';
end
def create
#welcome = 'world';
end
end
File: app/views/welcomes/index.html.rb
<%= form_for(#welcome) do |f| %>
<%= f.submit 'Submit' %>
<% end %>
File: app/views/welcomes/create.html.rb
<h1>Welcomes#create</h1>
<p>Find me in app/views/welcomes/create.html.erb</p>

Answer 2

I removed the below line in application.rb and the issue got resolved. config.assets.prefix="/chefUI"
I don't understand what config.assets.prefix has to do with POST requests, but this resolved my issue.
Would love to understand the reason though.