Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/8cef5b023344a0a1a8e2a940e49957b8.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563