Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/139e5f72a4b25a4db5ee26681c0f1d73.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563