Is it possible that you’ve mixed some old files in with your 3.4.0 files? It seems to me like the index.php script might be from an older version of OJS.
The index.php script should include the line:
require_once './lib/pkp/includes/bootstrap.php';
…but yours seems to include instead…
require_once './lib/pkp/includes/bootstrap.inc.php';
Regards,
Alec Smecher
Public Knowledge Project Team