Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/b1afe5872e2b9596b9f0b5bd4d925b14.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563