Php – Symfony2 dev environment works, prod environment gives 404 error

I have recently successfully installed Symfony2 on my machine.

I can access http:/localhost/app_dev.php (dev environment)

However, when I try to access the prod environment:

http:/localhost/app.php

I get the following error message in the browser:

Oops! An Error Occurred

The server returned a "404 Not Found".
Something is broken. Please e-mail us at [email] and let us know what
you were doing when this error occurred. We will fix it as soon as
possible. Sorry for any inconvenience caused.

I have checked the obvious: The file app.php does exist in the same folder as app_dev.php – so I don't know whats causing this.

Does anyone have a solution to fix this?

[[Edit]]

I have cleared the cache by typing: sudo php app/console cache:clear env=prod no-debug as recommended. I now get a blank screen. Worryingly, there are no error messages logged in app/logs/prod.log, so I have not got the faintest idea as to what is wrong (prod environment still works just fine).

Contents of my app/config/routing.yml file:

### fos routing, remove later
fos_user_security:
    resource: "@FOSUserBundle/Resources/config/routing/security.xml"

fos_user_profile:
    resource: "@FOSUserBundle/Resources/config/routing/profile.xml"
    prefix: /profile

fos_user_register:
    resource: "@FOSUserBundle/Resources/config/routing/registration.xml"
    prefix: /register

fos_user_resetting:
    resource: "@FOSUserBundle/Resources/config/routing/resetting.xml"
    prefix: /resetting

fos_user_change_password:
    resource: "@FOSUserBundle/Resources/config/routing/change_password.xml"
    prefix: /profile

###


# Internal routing configuration to handle ESI
#_internal:
#   resource: "@FrameworkBundle/Resources/config/routing/internal.xml"
#   prefix:   /_internal

Here is my app/config/routing_dev.yml file

_welcome:
    pattern:  /
    defaults: { _controller: AcmeDemoBundle:Welcome:index }

_demo_secured:
    resource: "@AcmeDemoBundle/Controller/SecuredController.php"
    type:     annotation

_demo:
    resource: "@AcmeDemoBundle/Controller/DemoController.php"
    type:     annotation
    prefix:   /demo

_assetic:
    resource: .
    type:     assetic

_wdt:
    resource: "@WebProfilerBundle/Resources/config/routing/wdt.xml"
    prefix:   /_wdt

_profiler:
    resource: "@WebProfilerBundle/Resources/config/routing/profiler.xml"
    prefix:   /_profiler

_configurator:
    resource: "@SensioDistributionBundle/Resources/config/routing/webconfigurator.xml"
    prefix:   /_configurator

_main:
    resource: routing.yml

I just noticed that I DO NOT have a routing_prod.yml**

(alarm bells ringing) – does Symfony2 not ship with a production routing config file?

My Apache configuration file content is shown below:

NameVirtualHost *:80

<VirtualHost *:80>
    DocumentRoot /path/to/symfony/web
    ServerName localhost

    # Custom log file
    Loglevel warn
    ErrorLog  /path/localhost.error.log
    CustomLog /path/localhost.access.log combined

    <Directory /path/to/symfony/web>
        AllowOverride None
        RewriteEngine On
        RewriteCond %{REQUEST_FILENAME} !-f 
        RewriteRule ^(.*)$ app.php [QSA,L]
    </Directory>
</VirtualHost>

[[Further Details]]

Contents of app/logs/prod.log

[2012-08-10 18:10:38] security.INFO: Populated SecurityContext with an
anonymous Token [] [] [2012-08-10 18:10:38] request.ERROR:
Symfony\Component\HttpKernel\Exception\NotFoundHttpException: No route
found for "GET /" (uncaught exception) at
/path/to/symfony/vendor/symfony/src/Symfony/Bundle/FrameworkBundle/EventListener/RouterListener.php
line 83 [] []