Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/fa295ef4d6f0ede8a4b80ac8a9a3091a.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563