Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/b063b355acf0e5fc37a1430ee1b5383e.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563