Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/4b6ce024e40b5b6f821b6eed8d1934d7.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563