Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/e17d3a2ce4c07802a720aa83e52b4c3e.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563