Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/40e6c6157e46b9e6e68369a64f1627cc.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563