Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/9e5e0c98e6f1202f1d84d4f8043d287a.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563