Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/0a8bef555fb4913b1c8fe12c4dee71de.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563