Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/d82b1a474e5a9a3114c53e9249a1a2f2.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563