Fatal error: Uncaught Error: Interface 'Zend_Filter_Interface' not found in C:\MANTUM\xampp2\htdocs\MNT\ventasvariables2\libreria\Zend\Filter\Alnum.php:37 Stack trace: #0 {main} thrown in C:\MANTUM\xampp2\htdocs\MNT\ventasvariables2\libreria\Zend\Filter\Alnum.php on line 37