[Symfony\Component\DependencyInjection\Exception\InvalidArgumentException]                         
                                                                                                       
    Unable to parse file "/var/www/xxx/vendor/braincrafted/bootstrap-bundle/Braincrafted/Bundle/B  
  ootstrapBundle/DependencyInjection/../Resources/config/services/form.xml".                           
                                                                                                       
                                                                                                       
                                                                                                       
                                                                                                       
    [InvalidArgumentException]                                                                         
                                                                                                       
    The XML file "/var/www/xxx/vendor/braincrafted/bootstrap-bundle/Braincrafted/Bundle/Bootstrap  
  Bundle/DependencyInjection/../Resources/config/services/form.xml" is not valid.                      
                                                                                                       
                                                                                                       
                                                                                                       
    [Symfony\Component\Debug\Exception\ContextErrorException]                                          
    Notice: Undefined property: DOMDocument::$documentElement                                          
                                                                                                       
  .