Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/f03e6590f89689827e9746d51537e6d0.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563