title: Class 'Psr\Log\LogLevel' not found in ErrorHandler.php
body: <p>using <code>composer update</code> or <code>composer install</code> getting this error:</p>
  
  <pre><code>Loading composer repositories with package information
  Installing dependencies (including require-dev) from lock file
  Nothing to install or update
  Generating autoload files
  &gt; Incenteev\ParameterHandler\ScriptHandler::buildParameters
  Updating the "app/config/parameters.yml" file
  &gt; Sensio\Bundle\DistributionBundle\Composer\ScriptHandler::buildBootstrap
  &gt; Sensio\Bundle\DistributionBundle\Composer\ScriptHandler::clearCache
  PHP Fatal error:  Class 'Psr\Log\LogLevel' not found in /var/www/html/Project/MRA/vendor/symfony/symfony/src/Symfony/Component/Debug/ErrorHandler.php on line 121
  Script Sensio\Bundle\DistributionBundle\Composer\ScriptHandler::clearCache handling the post-install-cmd event terminated with an exception
  
  
  
    [RuntimeException]                                                                                                                                             
    An error occurred when executing the "'cache:clear --no-warmup'" command:                                                                                      
    PHP Fatal error:  Class 'Psr\Log\LogLevel' not found in /var/www/html/Project/MRA/vendor/symfony/symfony/src/Symfony/Component/Debug/ErrorHandler.php on line  
     121                                                                                                                                                           
    .                                                                                                                                                              
  
  
  
  install [--prefer-source] [--prefer-dist] [--dry-run] [--dev] [--no-dev] [--no-plugins] [--no-custom-installers] [--no-autoloader] [--no-scripts] [--no-progress] [-v|vv|vvv|--verbose] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--ignore-platform-reqs] [--] [&lt;packages&gt;]...
  </code></pre>
  
  <p>I'm using symfony 2.7.7 and here is my composer.json:</p>
  
  <ul>
  <li>"php": ">=5.3.9",</li>
  <li>"symfony/symfony": "2.7.*",</li>
  <li>"doctrine/orm": "^2.4.8",</li>
  <li>"doctrine/doctrine-bundle": "~1.4",</li>
  <li>"symfony/assetic-bundle": "~2.3",</li>
  <li>"symfony/swiftmailer-bundle": "~2.3",</li>
  <li>"symfony/monolog-bundle": "~2.4",</li>
  <li>"sensio/distribution-bundle": "~4.0",</li>
  <li>"sensio/framework-extra-bundle": "^3.0.2",</li>
  <li>"incenteev/composer-parameter-handler": "~2.0",</li>
  <li>"friendsofsymfony/user-bundle": "~1.3",</li>
  <li>"mopa/bootstrap-bundle": "dev-master",</li>
  <li>"twbs/bootstrap": "^3.3",</li>
  <li>"knplabs/knp-paginator-bundle": "dev-master",</li>
  <li>"knplabs/knp-menu-bundle": "2.0.*@dev",</li>
  <li>"knplabs/knp-menu": "2.0.*@dev",</li>
  <li>"craue/formflow-bundle": "~2.0",</li>
  <li>"friendsofsymfony/rest-bundle": "^1.7",</li>
  <li>"sonata-project/admin-bundle": "2.3.*",</li>
  <li>"sonata-project/doctrine-orm-admin-bundle": "2.3.*",</li>
  <li>"sonata-project/user-bundle": "dev-master",</li>
  <li>"sonata-project/datagrid-bundle": "dev-master",</li>
  <li>"siphoc/pdf-bundle": "1.2.*",</li>
  <li>"knplabs/knp-snappy-bundle": "^1.3",</li>
  <li>"sonata-project/easy-extends-bundle": "^2.1"</li>
  </ul>