Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/c8e0ad71e011552a6abd0eac1d874f61.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563