title: SF2 app crash app_dev works
body: <p>I am working on a project under Symfony2.
  The project is actually online hosted by OVH. On this server everything is fine.
  But, we are changing host right now. I am trying to configure new host.</p>
  
  <p>I setup everything (SF2 works, mysql, apache too). When i launch web/app.php, the page stick blank, et I got these errors (on /var/log/apache2/error.log)</p>
  
  <pre><code>[Thu Jan 24 15:35:24 2013] [error] [client 31.39.43.247] PHP Warning:  mkdir(): Permission denied in /var/www/carpediese/app/cache/prod/classes.php on line 417
  [Thu Jan 24 15:35:24 2013] [error] [client 31.39.43.247] PHP Fatal error:  Uncaught exception 'UnexpectedValueException' with message 'The stream or file "/homez.577/carpedief/app/logs/prod.log" could not be opened: failed to open stream: No such file or directory' in /var/www/carpediese/app/cache/prod/classes.php:9762\nStack trace:\n#0 /var/www/carpediese/app/cache/prod/classes.php(9691): Monolog\\Handler\\StreamHandler-&gt;write(Array)\n#1 /var/www/carpediese/app/cache/prod/classes.php(9587): Monolog\\Handler\\AbstractProcessingHandler-&gt;handle(Array)\n#2 /var/www/carpediese/app/cache/prod/classes.php(9831): Monolog\\Handler\\AbstractHandler-&gt;handleBatch(Array)\n#3 /var/www/carpediese/app/ache/prod/classes.php(10113): Monolog\\Handler\\FingersCrossedHandler-&gt;handle(Array)\n#4 /var/www/carpediese/app/cache/prod/classes.php(10229): Monolog\\Logger-&gt;addRecord(500, 'InvalidArgument...', Array)\n#5 /var/www/carpediese/vendor/symfony/symfony/src/Symfony/Component/HttpKernel/EventListener/ExceptionListener.php(55): Monolog\\Logger-&gt;crit('InvalidArgument...')\n#6 [internal function]: Symfony\\Component\\HttpKer in /var/www/carpediese/app/cache/prod/classes.php on line 9762
  </code></pre>
  
  <p>I really dont know what is the error. Which files creates the errors ? All the files mentionned in the log seems to be cache files...
  I dont know what /homez.577 is ...</p>
  
  <p>app_dev works really fine, either on OVH server than the new.</p>
  
  <p>Do you got any ideas ?</p>
  
  <p>Edit</p>
  
  <p>I did the chmods.
  Now i got no more errors on apache2 logs.
  But (because there is always a but), when i load app.php, the page still stay blank.
  I try to clean the cache with the command u give me, here is tthe answer.</p>
  
  <p>Edit²</p>
  
  <p>So i find a solution. I still cant clean the cache with the command, but i did a rm -Rf app/cache </p>
  
  <p>Its working really nice. Thanky you dude!</p>