Apache+Passenger not serving the root of the Sinatra application

Since the last Fusion Passenger update, all my Sinatra applications have stopped working on the following env: Apache (2.4.17), Phusion Passenger (5.0.21). Everything was working as expected before updating the passenger middleware.

The problem is, apache directory is trying to proceed to a listing of the public directory when I'm requesting the url (https://myapp.ch) of my vhost.

The ODD part: If a route defined in the Sinatra controller is requested (i.e: https://myapp.ch/infos), passenger is started and the requested page is served as expected.

Here is the Virtual Host part:

<VirtualHost *:443>
  DocumentRoot /home/user1/sinatra/app1/public
  ServerName myapp.ch

  <Directory /home/user1/sinatra/app1/public>
      AllowOverride all
      Order allow,deny
      Allow from all
      Options -MultiViews
      Require all granted
  </Directory>

Config.ru

# encoding: UTF-8

require 'rubygems'
require 'sinatra'

require File.expand_path '../start.rb', __FILE__

run Sinatra::Application

Apache Log Error when requesting the root of the Sinatra App (/):

[Mon Oct 26 22:10:30.728795 2015] [autoindex:error] [pid 3535:tid 140103510914816] [client 176.127.182.162:50956] AH01276: Cannot serve directory /home/user1/sinatra/app1/public/: No matching DirectoryIndex (none) found, and server-generated directory index forbidden by Options directive

Apache is trying to do directory listing (which has been disabled by configuration).

Has someone experience the same issue ? How to make apache launch passager and serves the root of the Sinatra app ?