On a 100% fresh Drupal 7.56/CiviCRM 4.7.22 install, after entering all the db info in the CiviCRM installer and clicking "Check Requirements and Install CiviCRM", I get the following error:
Fatal error: Class 'Symfony\Component\DependencyInjection\ContainerBuilder' not found in ... /sites/all/modules/civicrm/Civi/Core/Container.php on line 104
I also got this same error when trying to perform an upgrade of an existing CiviCRM installation from an older version (4.4.5) to the latest. I thought a fresh install might be the fix, but apparently not.
I've searched documentation and Google for this error and found no real information on what could be causing it. All the server/database requirements are in place as far as I can tell, so I'm not sure if this is something any others have experienced? If anyone can shed any light on this error, it would be much appreciated. Thank you.