Fatal error: Uncaught Error: Class "Symfony\Component\Form\AbstractExtension" not found in I:\www\picman\vendor\symfony\form\Extension\HtmlSanitizer\HtmlSanitizerExtension.php:22 Stack trace: #0 {main} thrown in I:\www\picman\vendor\symfony\form\Extension\HtmlSanitizer\HtmlSanitizerExtension.php on line 22