Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/efd4fef36b351fe0e4f0ebe35c83c49d.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563