Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/288fa0d4c659d2d4d4f3800484c56a66.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563