title: An error occurred when executing the "'cache:clear --no-warmup'" command
body: <pre><code>[RuntimeException]                                                         
  An error occurred when executing the "'cache:clear --no-warmup'" command. 
  </code></pre>
  
  <p>i like to upgrade my symfony2.0 project to symfony 2.3 .</p>
  
  <p><a href="https://github.com/symfony/symfony-standard/blob/v2.3.1/UPGRADE.md" rel="noreferrer">https://github.com/symfony/symfony-standard/blob/v2.3.1/UPGRADE.md</a> </p>
  
  <p>i followed above one to upgrade my project .But i'm facing following errors </p>
  
  <pre><code>[RuntimeException]                                                         
  An error occurred when executing the "'cache:clear --no-warmup'" command.  
  </code></pre>