Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/f4aab960e60e4c61d96067dfa9612087.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563