Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/4ddd3b3ff2d4b5c1e06836a25f40e27b.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563